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Photography Techniques Advanced Skills

PDF generated using the open source mwlib toolkit. See http://code.pediapress.com/ for more information. PDF generated at: Wed, 21 Aug 2013 16:46:53 UTC Contents

Articles 1 High-dynamic-range imaging 8 Contre-jour 18 Night 20 Multiple 25 obscura 28 33 38 References Article Sources and Contributors 60 Image Sources, Licenses and Contributors 62 Article Licenses License 65 Zone System 1 Zone System

The Zone System is a photographic technique for determining optimal film exposure and development, formulated by and Fred Archer.[1] Adams described how the Zone System as "[...] not an invention of mine; it is a codification of the principles of , worked out by Fred Archer and myself at the Art Center School in Los Angeles, around 1939-40."[2] The technique is based on the late 19th century sensitometry studies of Hurter and Driffield. The Zone System provides photographers with a systematic method of precisely defining the relationship between the way they visualize the photographic subject and the final results. Although it originated with black-and-white , the Zone System is also applicable to roll film, both black-and-white and , and reversal, and to .

Principles

Visualization An expressive image involves the arrangement and rendering of various scene elements according to photographer’s desire. Achieving the desired image involves image management (placement of the camera, choice of , and possibly the use of camera movements) and control of image values. The Zone System is concerned with control of image values, ensuring that and dark values are rendered as desired. Anticipation of the final result before making the exposure is known as visualization.

Exposure metering Any scene of photographic interest contains elements of different luminance; consequently, the “exposure” actually is many different exposures. The exposure time is the same for all elements, but the image varies with the luminance of each subject element. Exposure is often determined using a reflected-light[3] exposure meter. The earliest meters measured overall average luminance; meter calibration was established to give satisfactory exposures for typical outdoor scenes. However, if the part of a scene that is metered includes large areas of unusually high or low reflectance, or unusually large areas of highlight or shadow, the “effective” average reflectance[4] may differ substantially from that of a “typical” scene, and the rendering may not be as desired. An averaging meter cannot distinguish between a subject of uniform luminance and one that consists of light and dark elements. When exposure is determined from average luminance measurements, the exposure of any given scene element depends on the relationship of its reflectance to the effective average reflectance. For example, a dark object of 4% reflectance would be given a different exposure in a scene of 20% effective average reflectance than it would be given in a scene of 12% reflectance. In a sunlit outdoor scene, the exposure for the dark object would also depend on whether the object was in sunlight or shade. Depending on the scene and the photographer’s , any of the previous exposures might be acceptable. However, in some situations, the photographer might wish to specifically control the rendering of the dark object; with overall average metering, this is difficult if not impossible. When it is important to control the rendering of specific scene elements, alternative metering techniques may be required. It is possible to make a meter reading of an individual scene element, but the exposure indicated by the meter will render that element as a medium gray; in the case of a dark object, that result is usually not what is desired. Even when metering individual scene elements, some adjustment of the indicated exposure is often needed if the metered scene element is to be rendered as visualized. Zone System 2

Exposure zones In the Zone System, measurements are made of individual scene elements, and exposure is adjusted based on the photographer’s knowledge of what is being metered: a photographer knows the difference between freshly fallen snow and a black horse, while a meter does not. Much has been written on the Zone System, but the concept is very simple—render light subjects as light, and dark subjects as dark, according to the photographer’s visualization. The Zone System assigns numbers from 0 through 10[5] to different brightness values, with 0 representing black, 5 middle gray, and 10 pure white; these values are known as zones. To make zones easily distinguishable from other quantities, Adams and Archer used Roman rather than Arabic numerals. Strictly speaking, zones refer to exposure,[6] with a Zone V exposure (the meter indication) resulting in a mid-tone rendering in the final image. Each zone differs from the preceding or following zone by a factor of two, so that a Zone I exposure is twice that of Zone 0, and so forth. A one-zone change is equal to one stop,[7] corresponding to standard and controls on a camera. Evaluating a scene is particularly easy with a meter that indicates in (EV), because a change of one EV is equal to a change of one zone. Many small- and medium-format include provision for ; this feature works well with the Zone System, especially if the camera includes spot metering, but obtaining proper results requires careful metering of individual scene elements and making appropriate adjustments.

Zones, the physical world and the print The relationship between the physical scene and the print is established by characteristics of the negative and the print. Exposure and development of the negative are usually determined so that a properly exposed negative will yield an acceptable print on a specific . Although zones directly relate to exposure, visualization relates to the final result. A black-and-white photographic print represents the visual world as a series of tones ranging from black to white. Imagine all of the tonal values that can appear in a print, represented as a continuous gradation from black to white:

Full Tonal Gradation

From this starting point, zones are formed by: •• Dividing the tonal gradation into eleven equal sections.

Eleven-Step Gradation

Note: You may need to adjust the brightness and of your monitor to see the gradations at the dark and light end of the scales. •• Blending each section into one tone that represents all the tonal values in that section. •• Numbering each section with Roman numerals from 0 for the black section to X for the white one.

Zone System 4

Exposure A dark surface under a bright light can reflect the same amount of light as a light surface under dim light. The human would perceive the two as being very different but a would measure only the amount of light reflected, and its recommended exposure would render either as Zone V. The Zone System provides a straightforward method for rendering these objects as the photographer desires. The key element in the scene is identified, and that element is placed on the desired zone; the other elements in the scene then fall where they may. With negative film, exposure often favors shadow detail; the procedure then is to 1.1.Visualize the darkest area of the subject in which detail is required, and place it on Zone III. The exposure for Zone III is important, because if the exposure is insufficient, the image may not have satisfactory shadow detail. If the shadow detail is not recorded at the time of exposure, nothing can be done to add it later. 2. Carefully meter the area visualized as Zone III and note the meter’s recommended exposure (the meter gives a Zone V exposure). 3. Adjust the recommended exposure so that the area is placed on Zone III rather than Zone V. To do this, use an exposure two stops less than the meter’s recommendation.

Development For every combination of film, developer, and paper there is a “normal” development time that will allow a properly exposed negative to give a reasonable print. In many cases, this means that values in the print will display as recorded (e.g., Zone V as Zone V, Zone VI as Zone VI, and so on). In general, optimal negative development will be different for every type and grade of paper. It is often desirable for a print to exhibit a full range of tonal values; this may not be possible for a low-contrast scene if the negative is given normal development. However, the development can be increased to increase the negative contrast so that the full range of tones is available. This technique is known as expansion, and the development usually referred to as “plus” or “N+”. Criteria for plus development vary among different photographers; Adams used it to raise a Zone VII placement to Zone VIII in the print, and referred to it as “N + 1” development. Conversely, if the negative for a high-contrast scene is given normal development, desired detail may be lost in either shadow or highlight areas, and the result may appear harsh. However, development can be reduced so that a scene element placed on Zone IX is rendered as Zone VIII in the print; this technique is known as contraction, and the development usually referred to as “minus” or “N−”. When the resulting change is one zone, it is usually called “N − 1” development. It sometimes is possible to make greater adjustments, using “N + 2” or “N − 2” development, and occasionally even beyond. Development has the greatest effect on dense areas of the negative, so that the high values can be adjusted with minimal effect on the low values. The effect of expansion or contraction gradually decreases with tones darker than Zone VIII (or whatever value is used for control of high values). Specific times for N+ or N− developments are determined either from systematic tests, or from development tables provided by certain Zone System books. Zone System 5

Additional processes Adams generally used selenium toning when processing prints. Selenium toner acts as a preservative and can alter the color of a print, but Adams used it subtly, primarily because it can add almost a full zone to the tonal range of the final print, producing richer dark tones that still hold shadow detail. His book The Print described using the techniques of to selectively darken or lighten areas of the final print. The Zone System requires that every variable in photography, from exposure to darkroom production of the print, be calibrated and controlled. The print is the last link in a chain of events, no less important to the Zone System than exposure and development of the film. With practice, the photographer visualizes the final print before the shutter is released.

Application to other media

Roll film Unlike sheet film, in which each negative can be individually developed, an entire roll must be given the same development, so that N+ and N− development are normally unavailable.[10] The key element in the scene is placed on the desired zone, and the rest of the scene falls where it will. Some contrast control is still available with the use of different paper grades. Adams (1981, 93–95) described use of the Zone System with roll film. In most cases, he recommended N − 1 development when a single roll was to be exposed under conditions of varying contrast, so that exposure could be sufficient to give adequate shadow detail but avoid excessive density and grain build-up in the highlights.

Color film Because of color shifts, color film usually does not lend itself to variations in development time. Use of the Zone System with color film is similar to that with black-and-white roll film, except that the exposure range is somewhat less, so that there are fewer zones between . The exposure scale of color is less than that of color negative film, and the procedure for exposure usually is different, favoring highlights rather than shadows; the shadow values then fall where they will. Whatever the exposure range, the meter indication results in a Zone V placement. Adams (1981, 95–97) described the application to color film, both negative and reversal.

Digital photography The Zone System can be used in digital photography just as in film photography; Adams (1981, xiii) himself anticipated the . As with color reversal film, the normal procedure is to expose for the highlights and process for the shadows. Until recently, digital sensors had a much narrower than color film, which, in turn, has less range than monochrome film. But an increasing number of digital cameras have wider dynamic ranges. One of the first was Fujifilm’s FinePix S3 Pro digital SLR, which has their proprietary “Super CCD SR sensor” specifically developed to overcome the issue of limited dynamic range, using interstitial low-sensitivity photosites () to capture highlight details.[citation needed] The CCD is thus able to expose at both low and high sensitivities within one shot by assigning a honeycomb of pixels to different intensities of light. Greater scene contrast can be accommodated by making one or more exposures of the same scene using different exposure settings and then combining those images. It often suffices to make two exposures, one for the shadows, and one for the highlights; the images are then overlapped and blended appropriately[11], so that the resulting composite represents a wider range of and tones. Combining images is often easier if the image-editing software includes features, such as the automatic layer alignment in CS3, that assist precise registration of multiple images. Even greater scene contrast can be handled by using more than two exposures and Zone System 6

combining with a feature such as Merge to HDR in Photoshop CS2 and later. The tonal range of the final image depends on the characteristics of the display medium. Monitor contrast can vary significantly, depending on the type (CRT, LCD, etc.), model, and calibration (or lack thereof). A computer ’s tonal output depends on the number of inks used and the paper on which it is printed. Similarly, the density range of a traditional photographic print depends on the processes used as well as the paper characteristics.

Histograms Most high-end digital cameras allow viewing a histogram of the tonal distribution of the captured image. This histogram, which shows the concentration of tones, running from dark on the left to light on the right, can be used to judge whether a full tonal range has been captured, or whether the exposure should be adjusted, such as by changing the exposure time, lens aperture, or ISO speed, to ensure a tonally rich starting image.[12]

Misconceptions and criticisms The Zone System gained an early reputation for being complex, difficult to understand, and impractical to apply to real-life shooting situations and equipment. Noted photographer Andreas Feininger wrote in 1976, I deliberately omitted discussing the so-called Zone System of film exposure determination in this book because in my opinion it makes mountains out of molehills, complicates matters out of all proportions, does not produce any results that cannot be accomplished more easily with methods discussed in this text, and is a ritual if not a form of cult rather than a practical technical procedure.[13] Much of the difficulty may have resulted from Adams’s early books, which he wrote without the assistance of a professional editor; he later conceded (Adams 1985, 325) that this was a mistake. Picker (1974) provided a concise and simple treatment that helped demystify the process. Adams’s later Photography Series published in the early 1980s (and written with the assistance of Robert Baker) also proved far more comprehensible to the average photographer. The Zone System has often been thought to apply only to certain materials, such as black-and-white sheet film and black-and-white photographic prints. Adams (1981, xii) suggested that when new materials become available, the Zone System is adapted rather than discarded. He anticipated the digital age, stating I believe the electronic image will be the next major advance. Such systems will have their own inherent and inescapable structural characteristics, and the artist and functional practitioner will again strive to comprehend and control them. Yet another misconception is that the Zone System emphasizes technique at the expense of creativity. Some practitioners have treated the Zone System as if it were an end in itself, but Adams made it clear that the Zone System was an enabling technique rather than the ultimate objective.

Notes

[3] Adams (1981, 30) considered the incident-light meter, which measures light falling on the subject, to be of limited usefulness because it takes no account of the specific subject luminances that actually produce the image. [4] A typical scene includes areas of highlight and shadow, and has scene elements at various angles to the light source, so it usually is possible to use the term “average” reflectance only loosely. Here, “effective” average reflectance is used to include these additional effects. [5][5]Adams (1981) designated 11 zones; other photographers, including Picker (1974) and White, Zakia, and Lorenz (1976) used 10 zones. Either approach is workable if the photographer is consistent in her methods. [6] Adams (1981) distinguished among exposure zones, negative density values, and print values. The negative density value is controlled by exposure and the negative development; the print value is controlled by the negative density value, and the paper exposure and development. Commonly, “zone” is also used, if somewhat loosely, to refer to negative density values and print values. [7] Photographers commonly refer to exposure changes in terms of “stops”, but properly, a stop is a device that regulates the amount of light, while a step is a division of a scale. The standard exposure scale consists of power-of-two steps; a one-step exposure increase doubles the exposure, while a one-step decrease halves the exposure. Davis (1999, 13) recommended the term “stop” to avoid confusion with the steps of a photographic step tablet, which may not correspond to standard power-of-two exposure steps. ISO standards generally use “step”. Zone System 7

[8] Adams’s description of zones and their application to typical scene elements was somewhat more extensive than the table in this article. The application of Zone IX to glaring snow is from Adams (1948). [9] The effective speed determined for a given combination of film and developer is sometimes described as an “Exposure Index” (EI), but an “EI” often represents a fairly arbitrary choice rather than the systematic speed determination done for use with the Zone System. [10] If a roll-film camera accepts interchangeable backs, it is possible to use N+ and N− development by designating different backs for different development, and changing backs when the image so requires. Without interchangeable backs, different camera bodies can be designated for different development, but this usually is practical only with small-format cameras.

[11] http:/ / www. luminous-landscape. com/ tutorials/ digital-blending. shtml

[12] Discussion on how histograms can be used to implement the Zone System in digital photography (http:/ / www. illustratedphotography.

com/ basic-photography/ zone-system-histograms) [13] Feininger, Andreas, Light and Lighting in Photography, Prentice-Hall, 1976

References • Adams, Ansel. 1948. The Negative: Exposure and Development. Ansel Adams Basic Photography Series/Book 2. Boston: New York Graphic Society. ISBN 0-8212-0717-2 • Adams, Ansel. 1981. The Negative. The New Ansel Adams Basic Photography Series/Book 2. ed. Robert Baker. Boston: New York Graphic Society. ISBN 0-8212-1131-5. Reprinted, Boston: Little, Brown, & Company, 1995. ISBN 0-8212-2186-8. Page references are to the 1981 edition. • Adams, Ansel. 1985. Ansel Adams: An Autobiography. ed. Mary Street Alinder. Boston: Little, Brown, & Company. ISBN 0-8212-1596-5 • ANSI PH2-1979. American National Standard Method for Determining Speed of Photographic Negative Materials (Monochrome, Continuous-Tone). New York: American National Standards Institute. • Davis, Phil. 1999. Beyond the Zone System. 4th ed. Boston: Focal Press. ISBN 0-240-80343-4 • ISO 6:1993. Photography—Black-and-White Pictorial Still Camera Negative Film/Process Systems. International

Organization for Standardization (http:/ / www. iso. org). • Latour, Ira H. 1998. Ansel Adams, The Zone System and the California School of Fine Arts. , v22, n2, Summer 1998, pg 148. ISSN 0308-7298/98. • Picker, Fred. 1974. Zone VI Workshop: The Fine Print in Black & White Photography. Garden City, N.Y.: Amphoto. ISBN 0-8174-0574-7 • White, Minor, Richard Zakia, and Peter Lorenz. 1976. The New Zone System Manual. Dobbs Ferry, N.Y.: Morgan & Morgan ISBN 0-87100-100-4

Further reading • Farzad, Bahman. The Confused Photographer’s Guide to Photographic Exposure and the Simplified Zone System. 4th ed. Birmingham, AL: Confused Photographer’s Guide Books, 2001. ISBN 0-9660817-1-4 • Johnson, Chris. The Practical Zone System, Fourth Edition: For Film and Digital Photography. 4th ed. Boston: Focal Press, 2007. ISBN 0-240-80756-1 • Lav, Brian. Zone System: Step-by-Step Guide for Photographers. Buffalo, NY: Amherst Media, 2001. ISBN 1-58428-055-7

High-dynamic-range imaging 9

High-dynamic-range imaging (HDRI or HDR) is a set of methods used in imaging and photography to capture a greater dynamic range between the lightest and darkest areas of an image than current standard digital imaging methods or photographic methods. HDR images can represent more accurately the range of intensity levels found in real scenes, from direct sunlight to faint starlight, and is often captured by way of a plurality of differently exposed pictures of the same subject matter.[1][][2] [3]

HDR methods provide higher dynamic range from the imaging process. Non-HDR cameras take pictures at one exposure level with a limited contrast range. This results in the loss of detail in bright or dark areas of a picture, depending on whether the camera Example of HDR image including images that were used for its creation. had a low or high exposure setting. HDR compensates for this loss of detail by taking multiple pictures at different exposure levels and intelligently stitching them together to produce a picture that is representative in both dark and bright areas. HDR is also commonly used to refer to display of images derived from HDR imaging in a way that exaggerates contrast for artistic effect. The two main sources of HDR images are computer renderings and merging of multiple low-dynamic-range (LDR)[4] or standard-dynamic-range (SDR)[5] . HDR images can also be acquired using special image sensors, HDR photography of Leukbach, a river of Saarburg, Germany. like oversampled binary . methods, which reduce overall contrast to facilitate display of HDR images on devices with lower dynamic range, can be applied to produce images with preserved or exaggerated local contrast for artistic effect. High-dynamic-range imaging 10

Photography

In photography, dynamic range is measured in EV differences (known as stops) between the brightest and darkest parts of the image that show detail. An increase of one EV or one stop is a doubling of the amount of light.

High-dynamic-range (HDR) image made out of three pictures. Taken in Tronador, Argentina.

Dynamic ranges of common devices

Device Stops Contrast

LCD display 9.5 700:1 (250:1 – 1750:1)

[] Negative film ( VISION3) 13 8192:1

[6] Human eye 10–14 1024:1 – 16384:1

[] DSLR camera ( K-5 II) 14.1 17560:1

High-dynamic-range photographs are generally achieved by capturing multiple standard photographs, often using exposure , and then merging them into an HDR image. Digital photographs are often encoded in a camera's , because 8 bit JPEG encoding doesn't offer enough values to allow fine transitions (and introduces undesirable effects due to the ). Any camera that allows manual exposure control can create HDR images. This includes film cameras, though the images may need to be digitized so they can be processed with software HDR methods. Some cameras have an auto exposure bracketing (AEB) feature with a far greater dynamic range than others, from the 3 EV of the Canon EOS 40D, to the 18 EV of the Canon EOS-1D Mark II.[7] As the popularity of this imaging method grows, several camera manufactures are now offering built-in HDR features. For example, the Pentax K-7 DSLR has an HDR mode that captures an HDR image and outputs (only) a tone mapped JPEG file.[8] The Canon PowerShot G12, Canon PowerShot S95 and Canon PowerShot S100 offer similar features in a smaller format.[9] Even some now include HDR modes, and most platforms have apps that provide HDR picture taking.[10] High-dynamic-range imaging 11

Editing Of all imaging tasks, demands the highest dynamic range. Editing operations need high precision to avoid aliasing artifacts such as banding and jaggies. Photoshop users are familiar with the issues of low dynamic range today. With 8 bit channels, if you brighten an image, information is lost irretrievably: darkening the image after brightening does not restore the original appearance. Instead, all of the highlights appear flat and washed out. One must work in a carefully planned work-flow to avoid this problem.

Scanning film In contrast to digital photographs, color negatives and slides consist of multiple film layers that respond to light differently. As a consequence, transparent originals (especially positive slides) feature a very high dynamic range.[11]

Dynamic ranges of photographic material

Material Dynamic range (F stops) Object contrast

print 5 1:32

color negative 8 1:256

positive slide 12 1:4096

When digitizing photographic material with an , the scanner must be able to capture the whole dynamic range of the original, or details are lost. The manufacturer's declarations concerning the dynamic range of flatbed and film scanners are often slightly inaccurate and exaggerated.[citation needed] Despite color negative having less dynamic range than slide, it actually captures considerably more dynamic range of the scene than does slide film. This dynamic range is simply compressed considerably.

Representing HDR images on LDR displays

Camera characteristics Camera characteristics must be considered when reconstructing high-dynamic-range images—particularly , sensor resolution, and noise.[]

Camera calibration Camera calibration can be divided into three aspects: geometric calibration, photometric calibration and spectral calibration. For HDR reconstruction, the important aspects are photometric and spectral calibrations.[]

Color reproduction Due to the fact that it is human of color rather than color per se that is important in color reproduction, light sensors and emitters try to render and manipulate a scene's light signal in such a way as to mimic human perception of color. Based on the trichromatic nature of the human eye, the standard solution adopted by industry is to use red, green, and blue filters, referred to as RGB, to sample the input light signal and to reproduce the signal using light-based image emitters. This employs an additive color model, as opposed to the subtractive color model used with printers, paintings etc. Photographic color films usually have three layers of emulsion, each with a different spectral , sensitive to red, green, and blue light, respectively. The RGB spectral response of the film is characterized by spectral sensitivity and spectral dye density curves.[12] High-dynamic-range imaging 12

Contrast reduction HDR images can easily be represented on common LDR media, such as computer monitors and photographic prints, by simply reducing the contrast, just as all image editing software is capable of doing.

Clipping and compressing dynamic range

Scenes with high dynamic ranges are often represented on LDR devices by cropping the dynamic range, cutting off the darkest and brightest details, or alternatively with an S-shaped conversion curve that compresses contrast progressively and more aggressively in the highlights and shadows while leaving the middle portions of the contrast range relatively unaffected.

Tone mapping An example of a rendering of an HDRI tone Tone mapping reduces the dynamic range, or contrast ratio, of the mapped image in a New York City nighttime entire image, while retaining localized contrast (between neighboring cityscape. pixels), tapping into research on how the human eye and visual cortex perceive a scene, trying to represent the whole dynamic range while retaining realistic color and contrast. Images with too much tone mapping processing have their range over-compressed, creating a surreal low-dynamic-range rendering of a high-dynamic-range scene.

Comparison with traditional digital images Information stored in high-dynamic-range images typically corresponds to the physical values of luminance or radiance that can be observed in the real world. This is different from traditional digital images, which represent colors that should appear on a monitor or a paper print. Therefore, HDR image formats are often called scene-referred, in contrast to traditional digital images, which are device-referred or output-referred. Furthermore, traditional images are usually encoded for the human visual system (maximizing the visual information stored in the fixed number of bits), which is usually called gamma encoding or . The values stored for HDR images are often gamma compressed (power law) or logarithmically encoded, or floating-point linear values, since fixed-point linear encodings are increasingly inefficient over higher dynamic ranges.[][13][14] HDR images often don't use fixed ranges per color channel—other than for traditional images—to represent many more colors over a much wider dynamic range. For that purpose, they don't user integer values to represent the single color channels (e.g.m, 0..255 in an 8 bit per interval for red, green and blue) but instead use a floating point representation. Common are 16-bit (half precision) or 32-bit floating point numbers to represent HDR pixels. However, when the appropriate transfer function is used, HDR pixels for some applications can be represented with as few as 10–12 bits for luminance and 8 bits for without introducing any visible quantization artifacts.[][15] High-dynamic-range imaging 13

History of HDR photography 1850 The idea of using several exposures to fix a too-extreme range of luminance was pioneered as early as the 1850s by Gustave Le Gray to render seascapes showing both the sky and the sea. Such rendering was impossible at the time using standard methods, the luminosity range being too extreme. Le Gray used one negative for the sky, and another one with a longer exposure for the sea, and combined the two into one picture in positive.[16]

Mid-twentieth century

Photo by Gustave Le Gray

External images

[17] [18][19] Schweitzer at the Lamp , by W. Eugene Smith

Mid-twentieth century, manual tone mapping was particularly done using dodging and burning – selectively increasing or decreasing the exposure of regions of the photograph to yield better tonality reproduction. This is effective because the dynamic range of the negative is significantly higher than would be available on the finished positive paper print when that is exposed via the negative in a uniform manner. An excellent example is the photograph Schweitzer at the Lamp by W. Eugene Smith, from his 1954 photo essay A Man of Mercy on Dr. Albert Schweitzer and his humanitarian work in French Equatorial Africa. The image took 5 days to reproduce the tonal range of the scene, which ranges from a bright lamp (relative to the scene) to a dark shadow.[19] Ansel Adams elevated dodging and burning to an art form. Many of his famous prints were manipulated in the darkroom with these two methods. Adams wrote a comprehensive book on producing prints called The Print, which features dodging and burning prominently, in the context of his Zone System. With the advent of , tone mapping in the darkroom was no longer possible, due to the specific timing needed during the developing process of color film. Photographers looked to film manufacturers to design new film stocks with improved response over the years, or shot in black and white to use tone mapping methods. High-dynamic-range imaging 14

Film capable of directly recording high-dynamic-range images was developed by Charles Wyckoff and EG&G "in the course of a contract with the Department of the Air Force".[20] This XR film had three layers, an upper layer having an ASA speed rating of 400, a middle layer with an intermediate rating, and a lower layer with an ASA rating of 0.004. The film was processed in a manner similar to color films, and each layer produced a different color.[21] The dynamic range of this extended range film has been estimated as 1:108.[22] It has been used to photograph [23] Exposure/Density Characteristics of Wyckoff's Extended Exposure Response Film nuclear explosions, for astronomical photography,[24] for spectrographic research,[25] and for medical imaging.[26] Wyckoff's detailed pictures of nuclear explosions appeared on the cover of Life magazine in the mid-1950s.

1980 The desirability of HDR has been recognized for decades, but its wider usage was, until quite recently, precluded by the limitations imposed by the available computer processing power. Probably the first practical application of HDRI was by the movie industry in late 1980s and, in 1985, Gregory Ward created the Radiance RGBE image format—the first HDR imaging file format. The concept of neighborhood tone mapping was applied to video cameras by a group from the Technion in Israel led by Prof. Y.Y.Zeevi who filed for a patent on this concept in 1988.[] In 1993 the first commercial medical camera was introduced that performed real time capturing of multiple images with different exposures, and producing an HDR video image, by the same group.[] Modern HDR imaging uses a completely different approach, based on making a high-dynamic-range luminance or light map using only global image operations (across the entire image), and then tone mapping this result. Global HDR was first introduced in 1993[1] resulting in a mathematical theory of differently exposed pictures of the same subject matter that was published in 1995 by Steve Mann and Rosalind Picard.[] This method was developed to produce a high-dynamic-range image from a set of photographs taken with a range of exposures. With the rising popularity of digital cameras and easy-to-use desktop software, the term HDR is now popularly used to refer to this process. This composite method is different from (and may be of lesser or greater quality than) the production of an image from one exposure of a sensor that has a native high dynamic range. Tone mapping is also used to display HDR images on devices with a low native dynamic range, such as a computer screen. 1996 The advent of consumer digital cameras produced a new demand for HDR imaging to improve the light response of sensors, which had a much smaller dynamic range than film. Steve Mann developed and patented the global-HDR method for producing digital images having extended dynamic range at the MIT Media Laboratory.[] Mann's method involved a two-step procedure: (1) generate one floating point image array by global-only image operations (operations that affect all pixels identically, without regard to their local neighborhoods); and then (2) convert this image array, using local neighborhood processing (tone-remapping, etc.), into an HDR image. The image array generated by the first step of Mann's process is called a lightspace image, lightspace picture, or radiance High-dynamic-range imaging 15

map. Another benefit of global-HDR imaging is that it provides access to the intermediate light or radiance map, which has been used for computer vision, and other image processing operations.[] 1997 This method of combining several differently exposed images to produce one HDR image was presented to the public by Paul Debevec. 2005 Photoshop CS2 introduced the Merge to HDR function, 32 bit floating point image support for HDR images, and HDR tone mapping for conversion of HDR images to LDR.[]

Video While custom high-dynamic-range digital video solutions had been developed for industrial manufacturing during the 1980s, it was not until the early that several scholarly research efforts used consumer-grade sensors and cameras.[27] A few companies such as RED[28] and Arri[29] have been developing digital sensors capable of a higher dynamic range. RED EPIC-X can capture HDRx images with a user selectable 1-3 stops of additional highlight latitude in the 'x' channel. The 'x' channel can be merged with the normal channel in post production software. With the advent of low-cost consumer digital cameras, many amateurs began posting tone mapped HDR time-lapse videos on the Internet, essentially a sequence of still photographs in quick succession. In 2010 the independent studio Soviet Montage produced an example of HDR video from disparately exposed video streams using a beam splitter and consumer grade HD video cameras.[30] Similar methods have been described in the academic literature in 2001[31] and 2007.[32] Modern movies have often been filmed with cameras featuring a higher dynamic range, and legacy movies can be upgraded even if manual intervention would be needed for some frames (as this happened in the past with black&white films’ upgrade to color). Also, special effects, especially those in which real and synthetic footage are seamlessly mixed, require both HDR shooting and rendering. HDR video is also needed in all applications in which capturing temporal aspects of changes in the scene demands high accuracy. This is especially important in monitoring of some industrial processes such as welding, predictive driver assistance systems in automotive industry, surveillance systems, to name just a few possible applications. HDR video can be also considered to speed up the image acquisition in all applications, in which a large number of static HDR images are needed, as for example in image-based methods in computer graphics. Finally, with the spread of TV sets with enhanced dynamic range, broadcasting HDR video may become important, but may take a long time to occur due to standardization issues. For this particular application, enhancing current low-dynamic range rendering (LDR) video signal to HDR by intelligent TV sets seems to be a more viable near-term solution.[33]

Examples These are examples of four standard dynamic range images that are combined to produce two resulting tone mapped images. Raw material

–4 stops –2 stops +2 stops +4 stops High-dynamic-range imaging 16

Results after processing

Simple contrast reduction Local tone mapping

These are examples of two standard dynamic range images that are combined to produce a resulting tone mapped image. Raw material

+2 stops -2 stops

Result after processing High-dynamic-range imaging 17

Final Tone Mapped Image

Gallery High-dynamic-range imaging 18

References

[1] "Compositing Multiple Pictures of the Same Scene", by Steve Mann, in IS&T's 46th Annual Conference, Cambridge, Massachusetts, May 9–14, 1993

[16] J. Paul Getty Museum. Gustave Le Gray, Photographer. July 9 – September 29, 2002. (http:/ / www. getty. edu/ art/ exhibitions/ le_gray) Retrieved September 14, 2008.

[17] http:/ / www. cybergrain. com/ tech/ hdr/ images1/ eugene_smith. jpg

[18] The Future of Digital Imaging – High Dynamic Range Photography (http:/ / www. cybergrain. com/ tech/ hdr/ ), Jon Meyer, Feb 2004

[19] 4.209: The Art and of Depiction (http:/ / people. csail. mit. edu/ fredo/ ArtAndScienceOfDepiction/ ), Frédo Durand and Julie

Dorsey, Limitations of the Medium: Compensation and accentuation – The Contrast is Limited (http:/ / people. csail. mit. edu/ fredo/

ArtAndScienceOfDepiction/ 12_Contrast/ contrast. html), lecture of Monday, April 9. 2001, slide 57–59 (http:/ / people. csail. mit. edu/ fredo/

ArtAndScienceOfDepiction/ 12_Contrast/ contrast6. ); image on slide 57, depiction of dodging and burning on slide 58 [21] C. W. Wyckoff. Experimental extended exposure response film. Society of Photographic Instrumentation Engineers Newsletter, June–July, 1962, pp. 16-20. [22] Michael Goesele, et al., "High Dynamic Range Techniques in Graphics: from Acquisition to Display", Eurographics 2005 Tutorial T7 (http:/

/ www. mpi-inf. mpg. de/ resources/ tmo/ EG05_HDRTutorial_Complete. pdf)

[23] The Militarily Critical List (http:/ / www. fas. org/ irp/ threat/ mctl98-2/ p2sec05. pdf) (1998), pages II-5-100 and II-5-107. [24] Andrew T. Young and Harold Boeschenstein, Jr., Isotherms in the region of Proclus at a phase angle of 9.8 degrees, Scientific Report No. 5, Harvard, College Observatory: Cambridge, Massachusetts, 1964. [28][28]UNIQ-nowiki-0-e3ee77f1e1218d46-QINU [29][29]UNIQ-nowiki-1-e3ee77f1e1218d46-QINU

Contre-jour

Contre-jour photo taken directly against the setting sun causing loss of subject detail and colour, and emphasis of shapes and lines. Medium: Colour digital image. Contre-jour 19

Contre-jour emphasizes the outline of the man and the tunnel entrance. The ground reflections show the position of the man. Medium: Digital scan from B&W paper print. Contre-jour, French for 'against daylight', refers to photographs taken when the camera is pointing directly toward a source of light. An alternative term is backlighting.[1][2] Contre-jour produces backlighting of the subject. This effect usually hides details, causes a stronger contrast between light and dark, creates silhouettes and emphasizes lines and shapes. The sun, or other light source, is often seen as either a bright spot or as a strong glare behind the subject.[2] Fill light may be used to illuminate the side of the subject facing toward the camera. Silhouetting occurs when there is a lighting ratio of 16:1 or more; at lower ratios such as 8:1 the result is instead called low-key lighting.[citation needed]

References

[1] "contre-jour" (http:/ / www. thefreedictionary. com/ contre-jour). The Free Dictionary. Retrieved 2011-04-16. [2] Freeman, Michael (2007) The Complete Guide to Light & Lighting in Digital Photography. ILEX, London: Lark Books. pp. 74&75. ISBN 978-1-57990-885-0. 20 Night photography

Night photography refers to photographs taken outdoors between dusk and dawn. Night photographers generally have a choice between using artificial light and using a long exposure, exposing the scene for seconds, minutes, and even hours in order to give the film or digital sensor enough time to capture a usable image. With the progress of high-speed films, higher-sensitivity digital image sensors, wide-aperture , and the ever-greater power of urban , night photography is increasingly possible using available light.

"The Night Sky" Photographed facing north at 6,600 feet (2,000 m) in the Mount Hood National Forest

The Skyline of Singapore as viewed at night

History

In the early 1900s, a few notable photographers, Alfred Stieglitz and William Fraser, began working at night. The first photographers known to have produced large bodies of work at night were Brassai and Bill Brandt. In 1932, Brassai published Paris de Nuit, a book of black-and-white photographs of the streets of Paris at night. During World War II, British photographer Brandt took advantage of the

black-out conditions to photograph the streets of London by moonlight. View of Al Ain from top of Jebel Hafeet Photography at night found several new practitioners in the 1970s, beginning with the black and white photographs that Richard Misrach made of desert flora (1975-77). Joel Meyerowitz made luminous color studies of Cape Cod at nightfall which were published in his influential book, Cape Light (1979). .Jan Staller’s twilight color Night photography 21

photographs (1977-84) of abandoned and derelict parts of New York City captured uncanny visons of the urban landscape lit by the glare of sodium vapor street lights. By the 1990s, British-born photographer Michael Kenna had established himself as the most commercially successful night photographer. His black-and-white landscapes were most often set between dusk and dawn in locations that included San Francisco, Japan, France, and England. Some of his most memorable projects depict the Ford Motor Company's Rouge River plant, the Ratcliffe-on-Soar Power Station in the East Early night photograph of the Luna Park, Coney Midlands in England, and many of the Nazi concentration Island, from the Detroit Publishing Co. collection, 1905. camps scattered across Germany, France, Belgium, Poland and Austria.

During the beginning of the 21st century, the popularity of digital cameras made it much easier for beginning photographers to understand the complexities of photographing at night. Today, there are hundreds of websites dedicated to night photography.

Subjects

• Celestial bodies (See .) • The moon, stars, planets, etc. Chay kenar Boulevard in Tabriz • City skylines • Factories and industrial areas, particularly those that are brightly lit and are emitting smoke or vapour •• Fireworks • Nightlife or rock concerts • Caves (See cave photography) • Streets with or without cars • Abandoned buildings and artificial structures that are lit only by moonlight • Bodies of water that are reflecting moonlight or city lights • Lakes, rivers, canals, etc. • Thunderstorms • Amusement rides Night photography 22

Technique and equipment

The following techniques and equipment are generally used in night photography. • A is usually necessary due to the long exposure times. Alternatively, the camera may be placed on a steady, flat object e.g. a table or chair, low wall, window sill, etc. • A shutter release cable or self timer is almost always used to prevent camera shake when the shutter is released. • Manual focus, since autofocus systems usually operate poorly in low light conditions. Newer digital cameras incorporate a Live View mode which often The length of a night exposure causes the lights on moving cars to allows very accurate manual focusing. streak across the image •• A stopwatch or remote timer, to time very long exposures where the camera's bulb setting is used.

Long exposures and multiple flashes The long exposure multiple technique is a method of night or low light photography which use a mobile flash unit to expose various parts of a building or interior using a long exposure. This technique is often combined with using coloured gels in front of the flash unit to provide different colours in order to illuminate the subject in different ways. It is also common to flash the unit several times during the exposure while swapping the colours of the gels around to mix colours on the final photo. This requires some skill and a lot of imagination since it is not possible to see how the effects will turn out until the exposure is complete. By using this technique, the photographer can illuminate specific parts of the subject in different colours creating shadows in ways which would not normally be possible.

Painting with light When the correct equipment is used such as a tripod and shutter release cable, the photographer can use long exposures to photograph images of light. For example, when photographing a subject try switching the exposure to manual and selecting the bulb setting on the camera. Once this is achieved trip the shutter and photograph your subject moving a flashlight or any small light in various patterns. Experiment with this outcome to produce artistic results. Multiple attempts are usually needed to produce a desired result. Night photography 23

High ISO With advance imaging sensor (CMOS-BSI) and sophisticated software (processor) we can make low-light photography with High ISO without tripod or long exposure and even can use cameras with small sensor such as: Cyber-shot DSC-RX100, 1 J2 and Canon PowerShot G1X which can give good images up to ISO 400.[1]

Examples

An exposure blended night image San Francisco – Oakland Rainbow Bridge viewed The Garden of Five of the Sydney Opera House Bay Bridge from Treasure from Odaiba Senses, Delhi Island (California) taken by Mikl Barton.

Amusement rides Four image panorama of The World The Golden Gate Bridge at Washington Park, 30 second Trade Center night. exposures each. in New York City.

Taipei 101 The Space Shuttle Toronto (30-second exposure). An exposure blended image at night, Columbia launches consisting of 30, 2.5 and 10 fully lit. for its mission to the second exposures Hubble Space Telescope.

University of New South Wales, Copenhagen at night Sydney (digital, night mode) Night photography 24

Published night photographers This section includes significant night photographers who have published books dedicated to night photography, and some of their selected works. •• Brassai • Paris de Nuit, Arts et metiers graphiques, 1932. •• Harold Burdekin and John Morrison • London Night, Collins, 1934. •• Jeff Brouws • Inside the Live Reptile Tent, Chronicle Books, 2001. ISBN 0-8118-2824-7 •• Alan Delaney • London After Dark, Phaidon Press, 1993. ISBN 0-7148-2870-X •• Neil Folberg • Celestial Nights, Aperture Foundation, 2001. ISBN 0-89381-945-X •• Karekin Goekjian • Light After Dark, Lucinne, Inc. ASIN B0006QOVCG •• Todd Hido • Outskirts, Nazraeli Press, 2002. ISBN 1-59005-028-2 •• Peter Hujar • Night, Matthew Marks Gallery/Fraenkel Gallery, 2005. ISBN 1-880146-45-2 •• Rolfe Horn • 28 Photographs, Nazraeli Press. ISBN 1-59005-122-X •• Lance Keimig •• Night Photography, Finding Your Way In The Dark, Focal Press, 2010. ISBN 978-0-240-81258-8 •• Brian Kelly • Grand Rapids: Night After Night, Glass Eye, 2001. ISBN 0-9701293-0-0 •• Michael Kenna • The Rouge, RAM Publications, 1995. ISBN 0-9630785-1-8 • Night Work, Nazraeli Press, 2000. ISBN 3-923922-83-3 •• William Lesch • Expansions, RAM Publications, 1992. ISBN 4-8457-0667-9 •• O. Winston Link • The Last Steam Railroad in America, Harry Abrams, 1995. ISBN 0-8109-3575-9 •• Tom Paiva • Industrial Night, The Image Room, 2002. ISBN 0-9716928-0-7 •• Troy Paiva • Night Vision: The Art of Urban Exploration, Chronicle Books, 2008. ISBN 0-8118-6338-7 • Lost America: The Abandoned Roadside West, MBI Publishing, 2003. ISBN 0-7603-1490-X •• Bill Schwab • Bill Schwab: Photographs, North Light Press, 1999. ISBN 0-9765193-0-5 • Gathering Calm, North Light Press, 2005. ISBN 0-9765193-2-1 • Jan Staller [2]

• Frontier New York, Hudson Hills Press, 1988. ISBN 1-55595-009-4,http:/ / www. janstaller. net/ books/ frontier-new-york/ Night photography 25

•• Zabrina Tipton • At Night in San Francisco, San Francisco Guild of the Arts Press, 2006. ISBN 1-4243-1882-3 •• Giovanna Tucker •• "How to Night Photography", 2011. ISBN 978-1-4657-4423-4 •• Volkmar Wentzel • Washington by Night, Fulcrum Publishing, 1998. ISBN 978-1-55591-410-3

References

[2] http:/ / www. janstaller. net/

External links

• Comprehensive tutorials and articles about how to do night photography (http:/ / thenocturnes. com/ resources. html) by The Nocturnes

• Photoblog Wiki (http:/ / www. photoblog. com/ wiki/ Night) Photoblog.com wiki article on night photography

• Short notes discussing the meaning and technique of night photography (http:/ / www. nightfolio. co. uk/

night_photography_notes_index. html) by David Baldwin

• Photography for night owls (http:/ / pages. cthome. net/ rwinkler/ nightphotog. htm) How to take photos in the style of Brassai

• Night Photography Guide (http:/ / adcuz. co. uk/ how-to-articles/ how-to-create-a-long-exposure-photo/ ) Tutorial by Adam Currie

Multiple exposure

In photography and cinematography, a is the superimposition of two or more exposures to create a single image, and double exposure has a corresponding meaning in respect of two images. The exposure values may or may not be identical to each other.

Overview

Ordinarily, cameras have a sensitivity to light that is a function of time. For example, a one second exposure is an exposure in which the camera image is equally responsive to light over the exposure time of one second. The criterion for determining that something is a double exposure is that the sensitivity goes up and then back down. The simplest example of a multiple exposure is a double exposure without flash, i.e. two partial exposures are made and then combined into one complete exposure. Some single exposures, such as "flash and blur" use A multiple exposure composite image of a lunar eclipse taken over a combination of electronic flash and ambient exposure. This effect can be Hayward, California in 2004. approximated by a Dirac delta measure (flash) and a constant finite rectangular window, in combination. For example, a sensitivity window comprising a Dirac comb combined with a rectangular pulse, is considered a multiple exposure, even though the sensitivity never goes to zero during the exposure. Multiple exposure 26

Double exposure

Analogue

In photography and cinematography, multiple exposure is a technique in which the camera shutter is opened more than once to expose the film multiple times, usually to different images. The resulting image contains the subsequent image/s superimposed over the original. The technique is sometimes used as an artistic visual effect and can be used to create ghostly images or to add people and objects to a scene that were not originally there. It is frequently used in photographic hoaxes. Composer Karlheinz Stockhausen, double It is considered easiest to have a manual winding camera for double exposure made using a film camera, 1980 exposures. On automatic winding cameras, as soon as a picture is taken the film is typically wound to the next frame. Some more advanced automatic winding cameras have the option for multiple exposures but it must be set before making each exposure. Manual winding cameras with a multiple exposure feature can be set to double-expose after making the first exposure. Since shooting multiple exposures will expose the same frame multiple times, negative exposure compensation must first be set to avoid overexposure. For example, to expose the frame twice with correct exposure, a −1 EV compensation have to be done, and −2 EV for Double exposure made using a film camera exposing four times. This may not be necessary when photographing a lit subject in two (or more) different positions against a perfectly dark background, as the background area will be essentially unexposed.

Medium to low light is ideal for double exposures. A tripod may not be necessary if combining different scenes in one shot. In some conditions, for example, recording the whole progress of a lunar eclipse in multiple exposures, a stable tripod is essential. More than two exposures can be combined, with care not to overexpose the film.

Digital

Digital enables images to be superimposed over each other by using a software photo editor, such as Adobe Photoshop or GIMP. These enable the opacity of the images to be altered and for an image to be overlayed over another. They also can set the layers to multiply mode, which 'adds' the colors together rather than making the colors of either image pale and translucent. Many digital SLR cameras allow multiple exposures to be made on the same image within the camera without the need for any external software.

Multiple exposure of one person using Adobe Photoshop Multiple exposure 27

Long exposures

With traditional film cameras, a long exposure is a single exposure, whereas with electronic cameras a long exposure can be obtained by integrating together many exposures. This averaging also permits there to be a time-windowing function, such as a Gaussian, that weights time periods near the center of the exposure time more strongly. Another possibility for synthesizing long exposure from multiple-exposure is to use an exponential decay in which the current frame has the strongest weight, and previous frames are faded out with a sliding exponential window. A four hour long exposure, using multiple shorter exposures

Scanning film with multiple exposure Multiple exposure technique can also be used when scanning transparencies like slides, film or negatives using a for increasing dynamic range. With multiple exposure the original gets scanned several times with different exposure intensities. An overexposed scan lights the shadow areas of the image and enables the scanner to capture more image information here. In contrary an underexposed scans allows to gather more details in the light areas. Afterwards the data can be calculated into a single HDR image with increased dynamic range. Among the scanning software solutions which implement multiple exposure are VueScan and SilverFast.

References 28 Camera obscura

The camera obscura (Latin; camera for "vaulted chamber/room", obscura for "dark", together "darkened chamber/room"; plural: camera obscuras or camerae obscurae) is an optical device that projects an image of its surroundings on a screen. It is used in drawing and for entertainment, and was one of the inventions that led to photography and the camera. The device consists of a box or room with a hole in one side. Light from an external scene passes through the hole and strikes a surface inside, where it is reproduced, upside-down, but with color and perspective preserved. The image can be projected onto paper, and can then be traced to produce a highly accurate A drawing of a camera obscura representation.The largest camera obscura in the world is on Constitution Hill in Aberystwyth, Wales.[1]

Using mirrors, as in the 18th-century overhead version (illustrated in the History section below), it is possible to project a right-side-up image. Another more portable type is a box with an angled mirror projecting onto tracing paper placed on the glass top, the image being upright as viewed from the back. As the pinhole is made smaller, the image gets sharper, but the projected image becomes dimmer. With too small a pinhole, however, Camerae obscurae for called the sharpness worsens, due to . Some practical camera "Grand Photographe" produced by Charles Chevalier (Musée des Arts et Métiers) obscuras use a lens rather than a pinhole because it allows a larger aperture, giving a usable brightness while maintaining focus. (See pinhole camera for construction information.)

A projection of an image of the New Royal Palace in Prague Castle created with a camera obscura Camera obscura 29

History

The camera obscura has been known to scholars since the time of Mozi and Aristotle.[2] The first surviving mention of the principles behind the pinhole camera or camera obscura belongs to Mozi (Mo-Ti) (470 to 390 BCE), a Chinese philosopher and the founder of Mohism.[3] Mozi referred to this device as a "collecting plate" or "locked treasure room."[4]

The Greek philosopher Aristotle (384 to 322 BCE) understood the optical principle of the pinhole camera.[5] He viewed the crescent shape of a partially eclipsed sun projected on the ground through the holes in a sieve and through the gaps between the leaves of a plane tree. In the 4th century BCE, Aristotle noted that "sunlight travelling through small openings between the leaves of a tree, the holes of a sieve, the openings wickerwork, and even interlaced fingers will create circular patches of light on the ground." Euclid's (ca 300 BCE) presupposed the camera obscura as a demonstration that light travels in straight lines.[6] In the 4th century, Greek scholar Theon of Alexandria observed that "candlelight passing through a pinhole will create an illuminated spot on a screen that is directly in line with the aperture Camera obscura in Encyclopédie, ou dictionnaire and the center of the candle." raisonné des , des arts et des métiers

In the 6th century, Byzantine mathematician and architect Anthemius of Tralles (most famous for designing the Hagia Sophia), used a type of camera obscura in his experiments.[] In the 9th century, Al-Kindi (Alkindus) demonstrated that "light from the right side of the flame will pass through the aperture and end up on the left side of the screen, while light from the left side of the flame will pass through the aperture and end up on the right side of the screen." Alhazen also gave the first clear description[7] and early analysis[8] of the camera obscura and pinhole camera. While Aristotle, Theon of Alexandria, Al-Kindi (Alkindus) and Chinese philosopher Mozi had earlier described the effects of a single light passing through a pinhole, none of them suggested that what is being projected onto the screen is an image of everything on the other side of the aperture. Alhazen was the first to demonstrate this with his lamp experiment where several different light sources are arranged across a large area. He was thus the first to successfully project an entire image from outdoors onto a screen indoors with the camera obscura. The Song Dynasty Chinese scientist Shen Kuo (1031–1095) experimented with a camera obscura, and was the first to apply geometrical and quantitative attributes to it in his book of 1088 AD, the Dream Pool Essays.[9]Wikipedia:Verifiability However, Shen Kuo alluded to the fact that the Miscellaneous Morsels from Youyang written in about 840 AD by Duan Chengshi (d. 863) during the Tang Dynasty (618–907) mentioned inverting the image of a Chinese pagoda tower beside a seashore.[9] In fact, Shen makes no assertion that he was the first to experiment with such a device.[9] Shen wrote of Cheng's book: "[Miscellaneous Morsels from Youyang] said that the image of the pagoda is inverted because it is beside the sea, and that the sea has that effect. This is nonsense. It is a normal principle that the image is inverted after passing through the small hole."[9] In 13th-century England, Roger Bacon described the use of a camera obscura for the safe observation of solar eclipses.[10] Its potential as a drawing aid may have been familiar to artists by as early as the 15th century; Leonardo da Vinci (1452–1519 AD) described the camera obscura in Codex Atlanticus. 's "Oculus Artificialis Teledioptricus Sive Telescopium, which was published in 1685, contains many descriptions and diagrams, illustrations and sketches of both the camera obscura and of the . Camera obscura 30

Giambattista della Porta is said to have perfected camera obscura. He described it as having a convex lens in later editions of his Magia Naturalis (1558-1589), the popularity of which helped spread knowledge of it. He compared the shape of the human eye to the lens in his camera obscura, and provided an easily understandable example of how light could bring images into the eye. One chapter in the Conte Algarotti's Saggio sopra Pittura (1764) is dedicated to the use of a camera ottica ("optic chamber") in painting.[11] The 17th century Dutch Masters, such as Johannes Vermeer, were known for their magnificent attention to detail. It has been widely speculated that they made use of such a camera, but the extent of their use by artists at this period remains a matter of considerable controversy, recently revived by the Hockney–Falco thesis.

The term "camera obscura" itself was first used by the German astronomer Johannes Kepler in 1604.[12] The English physician and author Sir Thomas Browne Camera obscura, from a manuscript of military designs. 17th century, speculated upon the interrelated workings of optics and possibly Italian. the camera obscura in his 1658 discourse The Garden of Cyrus thus:

For at the eye the Pyramidal rayes from the object, receive a decussation, and so strike a second base upon the Retina or hinder coat, the proper organ of Vision; wherein the pictures from objects are represented, answerable to the paper, or wall in the dark chamber; after the decussation of the rayes at the hole of the hornycoat, and their refraction upon the Christalline humour, answering the foramen of the window, and the convex or burning-, which refract the rayes that enter it. Early models were large; comprising either a whole darkened room or a tent (as employed by Johannes Kepler). By the 18th century, following developments by Robert Boyle and , more easily portable models became available. These were extensively used by amateur artists while on their travels, but they were also employed Four drawings by Canaletto, representing Campo San Giovanni e Paolo in Venice, obtained with a by professionals, including Paul Sandby, Canaletto and Joshua camera obscura (Venice, Gallerie Reynolds, whose camera (disguised as a book) is now in the Science dell'Accademia) Museum (London). Such cameras were later adapted by Joseph Nicephore Niepce, Louis Daguerre and William Fox Talbot for creating the first photographs. Camera obscura 31

Gallery

A freestanding room-sized A freestanding room-sized Image of the South Downs A camera obscura created camera obscura at the University camera obscura in the shape of of Sussex as seen in the by Mark Ellis is built in the of North Carolina at Chapel Hill. a camera located in San camera obscura of style of an Adirondack One of the pinholes can be seen Francisco at the Cliff House in Foredown Tower, mountain cabin, and sits by in the panel to the left of the Ocean Beach Portslade, England the shore of Lake Flower door. in the village of Saranac Lake, NY.

19th-century artist using a Image of a modern day camera Usage of a modern day camera camera obscura to outline obscura obscura used indoors his subject

In popular culture In the Mad Men (season 3) episode "Seven Twenty Three", Don Draper and Carlton Hanson help their children Sally Draper and Ernie Hanson's teacher, Suzanne Farrell, cut holes in cardboard boxes to create cameras obscurae, with which the kids and Miss Farrell watch the total solar eclipse of July 20, 1963; additionally, Betty Draper and Henry Francis encounter a couple in downtown Ossining using a similar device. Miss Farrell explains to the children and their fathers how it works and cautions against looking directly into the sun (which Betty Draper does, and as a result feels faint, afterward).[13]

Notes

[1] http:/ / www. cardiganshirecoastandcountry. com/ cliff-railway-camera-obscura-aberystwyth. php Cliff Railway and Camera Obscura, Aberystwyth

[2] Jan Campbell (2005). " Film and cinema spectatorship: melodrama and mimesis (http:/ / books. . com/ books?id=lOEqvkmSxhsC&

pg=PA114& dq& hl=en#v=onepage& q=& f=false)". Polity. p.114. ISBN 0-7456-2930-X [3] Needham, Joseph. (1986). Science and Civilization in China: Volume 4, and Physical Technology, Part 1, Physics. Taipei: Caves Books Ltd. Page 82. [4] Ouellette, Jennifer. (2005). Black Bodies and Quantum Cats: Tales from the Annals of Physics. London: Penguin Books Ltd. Page 52. [5] Aristotle, Problems, Book XV

[6] The Camera Obscura : Aristotle to Zahn (http:/ / inventors. about. com/ gi/ dynamic/ offsite. htm?site=http:/ / web. archive. org/ web/

20080420165232/ http:/ / www. acmi. net. au/ AIC/ CAMERA_OBSCURA. html) [7][7]: [8][8]: [9][9]Needham, Volume 4, Part 1, 98.

[10] BBC - The Camera Obscura (http:/ / www. bbc. co. uk/ dna/ h2g2/ A2875430)

[12] History of Photography and the Camera - Part 1: The first photographs (http:/ / inventors. about. com/ library/ inventors/ blphotography. htm) Camera obscura 32

References • Hill, Donald R. (1993), "Islamic Science and Engineering", Edinburgh University Press, page 70. • Lindberg, D.C. (1976), "Theories of Vision from Al Kindi to Kepler", The University of Chicago Press, Chicago and London. • Nazeef, Mustapha (1940), "Ibn Al-Haitham As a Naturalist Scientist", (Arabic), published proceedings of the Memorial Gathering of Al-Hacan Ibn Al-Haitham, 21 December 1939, Egypt Printing. • Needham, Joseph (1986). Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 1, Physics. Taipei: Caves Books Ltd. • Omar, S.B. (1977). "Ibn al-Haitham's Optics", Bibliotheca Islamica, Chicago. • Wade, Nicholas J.; Finger, Stanley (2001), "The eye as an optical instrument: from camera obscura to Helmholtz's

perspective", Perception 30 (10): 1157–1177, doi: 10.1068/p3210 (http:/ / dx. doi. org/ 10. 1068/ p3210), PMID

11721819 (http:/ / www. ncbi. nlm. nih. gov/ pubmed/ 11721819)

External links • Timeline - The Camera Obscura in History The Camera Obscura Journal. Sfumato Press One error on page.

Nicéphore Niépce did not use a pinhole camera in 1827 - he used a camera obscura with a lens. (http:/ / www.

obscurajournal. com/ history. php)

• An Appreciation of the Camera Obscura (http:/ / brightbytes. com/ cosite/ cohome. html)

• The Camera Obscura in San Francisco (http:/ / www. giantcamera. com/ ) – the Giant Camera of San Francisco at Ocean Beach, added to the National Register of Historic Places in 2001

• Camera Obscura and World of Illusions (http:/ / www. camera-obscura. co. uk/ ), Edinburgh

• Dumfries Museum & Camera Obscura, Dumfries, Scotland (http:/ / www. dumfriesmuseum. demon. co. uk/

dumfmuse. html)

• Vermeer and the Camera Obscura (http:/ / www. bbc. co. uk/ history/ british/ empire_seapower/

vermeer_camera_01. shtml) by Philip Steadman

• Paleo-camera (http:/ / www. paleo-camera. com/ ) – the camera obscura and the origins of art

• List of all known Camera Obscura (http:/ / www. foredown. virtualmuseum. info/ camera_obscuras/ default. asp)

• Willett & Patteson (http:/ / www. amazingcameraobscura. co. uk) Camera obscura hire and creation

• Camera Obscura and Outlook Tower, Edinburgh, Scotland (http:/ / www. scottish-places. info/ features/

featurefirst1049. html)

• Cameraobscuras.com (http:/ / www. cameraobscuras. com) George T Keene builds custom camera obscuras like the Griffith Observatory CO in Los Angeles.

• Camera obscura in Trondheim, Norway (http:/ / www. ntnu. no/ 1-2-tre/ 06), built by students of architecture and engineering from Norwegian University of Science and Technology (NTNU)

Pinhole camera 34

A common use of the pinhole camera is to capture the movement of the sun over a long period of time. This type of photography is called Solargraphy. The image may be projected onto a translucent screen for real-time viewing (popular for observing solar eclipses; see also camera obscura), or can expose or a charge coupled device (CCD). Pinhole cameras with CCDs are often used for surveillance[citation needed] because they are difficult to detect.

Pinhole devices provide safety for the when viewing solar Holes in the canopy project images of a solar eclipses because the event is observed indirectly, the diminished eclipse on the ground. intensity of the pinhole image being harmless compared with the full glare of the Sun itself.[citation needed] World Pinhole Day is held on the last Sunday of April.[1]

Invention of pinhole camera

In the 10th century, Persian scientist Ibn al-Haytham (Alhazen) wrote about naturally-occurring rudimentary pinhole cameras. For example, light may travel through the slits of wicker baskets or the crossing of tree leaves.[2] (The circular dapples on a forest floor, actually pinhole A home-made pinhole camera (on the left), wrapped in black plastic to prevent light leaks, images of the sun, can be seen to have a bite taken out of them during and related developing supplies. partial solar eclipses opposite to the position of the moon's actual occultation of the sun because of the inverting effect of pinhole lenses.)

Alhazen published this idea in the Book of Optics in 1021 AD. He improved on the camera after realizing that the smaller the pinhole, the sharper the image (though the less light). He provides the first clear description for construction of a camera obscura (Lat. dark chamber).

In the 5th century BC, the Mohist philosopher Mozi (墨 子) in ancient China mentioned the effect of an inverted image forming through a pinhole.[3] The image of an inverted Chinese pagoda is mentioned in Duan Chengshi's (d. 863) book Miscellaneous Morsels from Youyang written during the Tang Dynasty (618–907).[4] Along with experimenting with the pinhole camera and the burning mirror of the ancient Mohists, the Song Dynasty (960–1279 CE) Chinese scientist Shen Kuo (1031–1095) experimented with camera obscura and was the first to establish geometrical and quantitative attributes for it.[4] In the 13th century, Robert Grosseteste and Roger Bacon commented on the pinhole camera.[5] Between 1000 and 1600, men such as Ibn al-Haytham, Gemma Frisius, and Giambattista della Porta wrote on the pinhole camera, explaining why the images are upside down. Around 1600, Giambattista della Porta added a lens to the pinhole camera.[6][7] It was not until 1850 that a Scottish scientist by the name of Sir David Brewster actually took the first photograph with a pinhole camera. Up until recently it was believed that Brewster himself coined the term "Pinhole" in "The "[citation needed]. The earliest Ancient pinhole camera effect caused by reference to the term "Pinhole" has been traced back to almost a balistrarias in the Castelgrande in Bellinzona century before Brewster to James Ferguson's Lectures on select Subjects.[8][9] Sir William Crookes and William de Wiveleslie Abney were other early photographers to try the pinhole technique.[10] Pinhole camera 35

Selection of pinhole size

Within limits, a smaller pinhole (with a thinner surface that the hole goes through) will result in sharper because the projected at the image plane is practically the same size as the pinhole. An extremely small hole, however, can produce significant diffraction effects and a less clear image due to the wave properties of light.[] Additionally, occurs as the diameter of the hole approaches the thickness of the material in which it is An example of a 20 minute exposure taken with a pinhole camera punched, because the sides of the hole obstruct the light entering at anything other than 90 degrees.

The best pinhole is perfectly round (since irregularities cause higher-order diffraction effects), and in an extremely thin piece of material. Industrially produced pinholes benefit from etching, but a hobbyist can still produce pinholes of sufficiently high quality for photographic work.

A photograph taken with a pinhole camera using an exposure time of 2s

One method is to start with a sheet of brass shim or metal reclaimed from an aluminium drinks can or tin foil/aluminum foil, use fine sand paper to reduce the thickness of the centre of the material to the minimum, before carefully creating a pinhole with a suitably sized needle. A method of calculating the optimal pinhole diameter was first attempted by Jozef Petzval. The crispest image is obtained using a pinhole size determined by the formula[11]

where d is pinhole diameter, f is (distance from pinhole to image plane) and λ is the of light. For standard black-and-white film, a wavelength of light corresponding to yellow-green (550 nm) should yield optimum results. For a pinhole-to-film distance of 1 inch (25 mm), this works out to a pinhole Some examples of photographs taken using a 0.17 mm in diameter.[12] For 5 cm, the appropriate diameter is pinhole camera. 0.23 mm.[13] The is basically infinite, but this does not mean that no optical blurring occurs. The infinite depth of field means that image blur depends not on object distance, but on other factors, such as the distance from the aperture to the film plane, the aperture size, and the wavelength(s) of the light source. Pinhole camera 36

Pinhole camera construction Pinhole cameras can be handmade by the photographer for a particular purpose. In its simplest form, the photographic pinhole camera can consist of a light-tight box with a pinhole in one end, and a piece of film or photographic paper wedged or taped into the other end. A flap of cardboard with a tape hinge can be used as a shutter. The pinhole may be punched or drilled using a sewing needle or small diameter bit through a piece of tinfoil or thin aluminum or brass sheet. This piece is then taped to the inside of the light tight box behind a hole cut through the box. A cylindrical oatmeal container may be made into a pinhole camera. Pinhole cameras can be constructed with a sliding or back so the distance between the film and the pinhole can be adjusted. This allows the of the camera to be changed and also the effective f-stop ratio of the camera. Moving the film closer to the pinhole will result in a wide angle field of view and a shorter exposure time. Moving the film farther away from the pinhole will result in a telephoto or narrow angle view and a longer exposure time. Pinhole cameras can also be constructed by replacing the lens assembly in a conventional camera with a pinhole. In particular, compact 35 mm cameras whose lens and focusing assembly have been damaged can be reused as pinhole cameras—maintaining the use of the shutter and film winding mechanisms. As a result of the enormous increase in f-number while maintaining the same exposure time, one must use a fast film in direct sunshine. Pinholes (homemade or commercial) can be used in place of the lens on an SLR. Use with a digital SLR allows metering and composition by trial and error, and is effectively free, so is a popular way to try pinhole photography.[14] Unusual materials have been used to construct pinhole cameras, e.g., a Chinese roast duck.[15] by Martin Cheung

Calculating the f-number & required exposure Pinhole camera 37

The f-number of the camera may be calculated by dividing the distance from the pinhole to the imaging plane (the focal length) by the diameter of the pinhole. For example, a camera with a 0.5 mm diameter pinhole, and a 50 mm focal length would have an f-number of 50/0.5, or 100 (f/100 in conventional notation). Due to the large f-number of a pinhole camera, exposures will often encounter reciprocity failure.[16] Once exposure time has exceeded about 1 second for film or 30 seconds for paper, one must compensate for the breakdown in linear response of the film/paper to intensity of illumination by using longer exposures. Other special features can be built into pinhole cameras such as the ability to take double images, by using multiple pinholes, or the ability to take pictures in cylindrical or spherical perspective by curving the film plane. These characteristics could be used for creative purposes. Once considered as an obsolete technique from the early days of photography, pinhole photography is from time to time a trend in artistic photography.

Related cameras, image forming devices, or developments from it A pinhole camera made from an oatmeal box. include Franke's widefield pinhole camera, the pinspeck camera, and The pinhole is in the center. The black plastic which normally surrounds this camera (see the pinhead mirror. picture above) has been removed. NASA (via the NASA Institute for Advanced Concepts) has funded initial research into the New Worlds Mission project, which proposes to use a pinhole camera with a diameter of 10 m and focus length of 200,000 km to image earth sized planets in other star systems.

Coded

A non-focusing coded-aperture optical system may be thought of as multiple pinhole cameras in conjunction. By adding pinholes, light throughput and thus sensitivity are increased. However, multiple images are formed, usually requiring computer deconvolution.

References

[1] http:/ / www. bbc. co. uk/ news/ in-pictures-22150973

[2] "Light Through the Ages" (http:/ / www-groups. dcs. st-and. ac. uk/ ~history/

HistTopics/ Light_1. html). [3] Needham, Joseph (1986). Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 1, Physics. Taipei: Caves Books Ltd. Page 82. [4] Needham, Joseph (1986). Science and Civilization in China: Volume 4, Physics and A fire hydrant photographed by a pinhole camera Physical Technology, Part 1, Physics. Taipei: Caves Books Ltd. Page 98. made from a shoe box, exposed on photographic

[5] A reconsideration of Roger Bacon's theory of pinhole images (http:/ / www. paper (top). The length of the exposure was 40

springerlink. com/ index/ R2717G210K21R7R2. pdf) seconds. There is noticeable flaring in the bottom-right corner of the image, likely due to [6] History of Photography and the Camera – Pinhole Camera to Daguerreotype (http:/ / extraneous light entering the camera box. inventors. about. com/ library/ inventors/ blphotography. htm)

[7] http:/ / www-history. mcs. st-andrews. ac. uk/ Biographies/ Porta. html

[9] What is a Pinhole Camera? (http:/ / www. pinhole. cz/ en/ pinholecameras/ whatis. html) Pinhole camera 38

[10] Pinhole photography history (http:/ / photo. net/ learn/ pinhole/ pinhole)

[11] Rayleigh, (1891) Lord Rayleigh on Pin-hole Photography (http:/ / idea. uwosh. edu/ nick/ rayleigh. pdf) in Philosophical Magazine, vol.31, pp. 87–99 presents his formal analysis, but the layman's formula "pinhole radius = √(ƒλ)" appears in Strutt,J.W. Lord Rayleigh (1891) Some applications of photography in Nature. Vol.44 p.254.

[12] Equation for calculation with f=1in, using Google for evaluation (http:/ / www. google. com/ search?q=sqrt(2*1in*550nm)=)

[13] Equation for calculation with f=5cm, using Google for evaluation (http:/ / www. google. com/ search?q=+ sqrt(2*5cm*550nm)=)

[14] http:/ / www. pcw. co. uk/ personal-computer-world/ features/ 2213298/ hands-digital-pinhole-camera

[15] http:/ / www. urbanphoto. net/ blog/ 2010/ 11/ 25/ how-a-roast-duck-sees-chinatown/

[16] http:/ / www. nancybreslin. com/ pinholetech. html

External links

• Pinhole Photography by Vladimir Zivkovic (http:/ / www. behance. net/ gallery/

PICTORIALISM-Winter-Pinhole-Photography/ 897715)

• Worldwide Pinhole Photography Day website (http:/ / www. pinholeday. org/ gallery/ index. php)

• An easy way to convert a DSLR to a pinhole camera (http:/ / www. alistairscott. com/ howto/ pinhole/ )

• Pinhole Photography and Camera Design Calculators (http:/ / www. mrpinhole. com/ )

• Illustrated history of cinematography (http:/ / www. precinemahistory. net/ )

• How to Make and Use a Pinhole Camera (http:/ / www. kodak. com/ global/ en/ consumer/ education/

lessonPlans/ pinholeCamera/ pinholeCanBox. shtml)

• Oregon Art Beat: Pinhole Photos by Zeb Andrews (http:/ / watch. opb. org/ video/ 2364990891)

Stereoscopy

Stereoscopy (also called stereoscopics or 3D imaging) is a technique for creating or enhancing the illusion of depth in an image by means of for . The word stereoscopy derives from the Greek "στερεός" (stereos), "firm, solid"[1] + "σκοπέω" (skopeō), "to look", "to see".[2] Most stereoscopic methods present two offset images separately to the left and right eye of the viewer. These two-dimensional images are then combined in the brain to give the perception of 3D depth. This technique is distinguished from 3D displays that display an image in Pocket stereoscope with original test image. Used by military to examine stereoscopic pairs of aerial three full dimensions, allowing the observer to increase information photographs. about the 3-dimensional objects being displayed by head and eye movements.

Background

Stereoscopy creates the illusion of three-dimensional depth from given two-dimensional images. Human vision, including the perception of depth, is a complex process which only begins with the acquisition of visual information taken in through the eyes; much processing ensues View of Boston, c. 1860; an early stereoscopic within the brain, as it strives to make intelligent and meaningful sense card for viewing a scene from nature of the raw information provided. One of the very important visual functions that occur within the brain as it interprets what the eyes see is Stereoscopy 39

that of assessing the relative distances of various objects from the viewer, and the depth dimension of those same perceived objects. The brain makes use of a number of cues to determine relative distances and depth in a perceived scene, including:[3] •• Stereopsis •• Accommodation of the eye •• Overlapping of one object by another

•• Subtended visual angle of an object of known size Kaiserpanorama consisted of a multi-station •• Linear perspective (convergence of parallel edges) viewing apparatus and sets of stereo slides. [] •• Vertical position (objects higher in the scene generally tend to be Patented by A. Fuhrmann around 1890. perceived as further away) •• Haze, desaturation, and a shift to bluishness •• Change in size of textured pattern detail (All the above cues, with the exception of the first two, are present in traditional two-dimensional images such as paintings, photographs, and television.) Stereoscopy is the production of the illusion of depth in a photograph, movie, or other two-dimensional image by presenting a slightly different image to each eye, and thereby adding the first of these cues (stereopsis) as well. Both of the 2D offset images are then combined in the brain to give the perception of 3D depth. It is important to note that Company of ladies watching stereoscopic since all points in the image focus at the same plane regardless of their photographs, painting by Jacob Spoel, before depth in the original scene, the second cue, focus, is still not duplicated 1868. A very early depiction of people using a and therefore the illusion of depth is incomplete. There are also stereoscope. primarily two effects of stereoscopy that are unnatural for the human vision: first, the mismatch between convergence and accommodation, caused by the difference between an object's perceived position in front of or behind the display or screen and the real origin of that light and second, possible crosstalk between the eyes, caused by imperfect image separation by some methods.

Although the term "3D" is ubiquitously used, it is also important to note that the presentation of dual 2D images is distinctly different from displaying an image in three full dimensions. The most notable difference is that, in the case of "3D" displays, the observer's head and eye movement will not increase information about the 3-dimensional objects being displayed. Holographic displays or are examples of displays that do not have this limitation. Similar to the technology of sound reproduction, in which it is not possible to recreate a full 3-dimensional sound field merely with two stereophonic speakers, it is likewise an overstatement of capability to refer to dual 2D images as being "3D". The accurate term "stereoscopic" is more cumbersome than the common misnomer "3D", which has been entrenched after many decades of unquestioned misuse. Although most stereoscopic displays do not qualify as real 3D display, all real 3D displays are also stereoscopic displays because they meet the lower criteria as well.

Most 3D displays use this stereoscopic method to convey images. It was first invented by Sir Charles Wheatstone in 1838.[4][5] Stereoscopy 40

Wheatstone originally used his stereoscope (a rather bulky device)[6] with drawings because photography was not yet available, yet his original paper seems to foresee the development of a realistic imaging method:[7] For the purposes of illustration I have employed only outline figures, for had either shading or colouring been

introduced it might be supposed that the effect was wholly Wheatstone mirror stereoscope or in part due to these circumstances, whereas by leaving them out of consideration no room is left to doubt that the entire effect of relief is owing to the simultaneous perception of the two monocular projections, one on each retina. But if it be required to obtain the most faithful resemblances of real objects, shadowing and colouring may properly be employed to heighten the effects. Careful attention would enable an artist to draw and paint the two component pictures, so as to present to the mind of the observer, in the resultant perception, perfect identity with the object represented. Flowers, crystals, busts, vases, instruments of various kinds, &c., might thus be represented so as not to be distinguished by sight from the real objects themselves.[4]

Stereoscopy is used in photogrammetry and also for entertainment through the production of stereograms. Stereoscopy is useful in viewing images rendered from large multi-dimensional data sets such as are produced by experimental data. An early patent for 3D imaging in cinema and television was granted to physicist Theodor V. Ionescu in 1936. Modern industrial three-dimensional photography may use 3D scanners to detect and record three-dimensional information.[8] The three-dimensional depth information can be reconstructed from two images using a computer by corresponding the pixels in the left and right images (e.g.,[9]). Solving the in the field of Computer Vision aims to create meaningful depth information from two images.

Visual requirements Anatomically, there are 3 levels of binocular vision required to view stereo images: 1.1.Simultaneous perception 2.2.Fusion (binocular 'single' vision) 3.3.Stereopsis These functions develop in early childhood. Some people who have strabismus disrupt the development of stereopsis, however orthoptics treatment can be used to improve binocular vision. A person's stereoacuity determines the minimum image disparity they can perceive as depth. It is believed that approximately 12% of people are unable to properly see 3D images, due to a variety of medical conditions.[10][11] According to another experiment up to 30% of people have very weak stereoscopic vision preventing them from based on stereo disparity. This nullifies or greatly decreases immersion effects of stereo to them.[12] Stereoscopy 41

Side-by-side

Traditional stereoscopic photography consists of creating a 3D illusion starting from a pair of 2D images, a stereogram. The easiest way to enhance depth perception in the brain is to provide the eyes of the viewer with two different images, representing two perspectives of the same object, with a minor deviation equal or nearly equal to the perspectives that both eyes naturally receive in binocular vision. "The early bird catches the worm" Stereograph To avoid eyestrain and , each of the two 2D images should be published in 1900 by North-Western View Co. of presented to the viewer so that any object at infinite distance is Baraboo, Wisconsin, digitally restored. perceived by the eye as being straight ahead, the viewer's eyes being neither crossed nor diverging. When the picture contains no object at infinite distance, such as a horizon or a cloud, the pictures should be spaced correspondingly closer together. The principal advantages of side-by-side viewers is the lack of diminution of brightness, allowing the presentation of images at very high resolution and in full spectrum color, in creation, and little or no additional image processing is required. Under some circumstances, such as when a pair of images are presented for freeviewing, no device or additional optical equipment is needed. The principal disadvantage of side-by-side viewers is that large image displays are not practical and resolution is limited by the lesser of the display medium or human eye. This is because as the dimensions of an image are increased, either the viewing apparatus or viewer themselves must move proportionately further away from it in order to view it comfortably. Moving closer to an image in order to see more detail would only be possible with viewing equipment that adjusted to the difference.

Freeviewing

Freeviewing is viewing a side-by-side image pair without using a viewing device.[13] Two methods are available to freeview:[14][15] • The parallel viewing method uses an image pair with the left-eye image on the left and the right-eye image on the right. The fused three-dimensional image appears larger and more distant than the two actual images, making it possible to convincingly simulate a life-size scene. The viewer attempts to look through the images with the eyes substantially parallel, as if looking at the actual scene. This can be difficult with normal vision because eye focus and binocular convergence are habitually coordinated. One approach to decoupling the two functions is to view the image pair extremely close up with completely relaxed eyes, making no attempt to focus

clearly but simply achieving comfortable stereoscopic fusion of the Printable cross eye viewer. two blurry images by the "look-through" approach, and only then exerting the effort to focus them more clearly, increasing the viewing distance as necessary. Regardless of the approach used or the image medium, for comfortable viewing and stereoscopic accuracy the size and spacing of the images should be such that the corresponding points of very distant objects in the scene are separated by the same distance as the viewer's eyes, but not more; the average interocular distance is about 63 mm. Viewing much more widely separated images is possible, but because the eyes never diverge in normal use it usually requires some previous training and tends to cause eye strain. Stereoscopy 42

•• The cross-eyed viewing method swaps the left and right eye images so that they will be correctly seen cross-eyed, the left eye viewing the image on the right and vice-versa. The fused three-dimensional image appears to be smaller and closer than the actual images, so that large objects and scenes appear miniaturized. This method is usually easier for freeviewing novices. As an aid to fusion, a fingertip can be placed just below the division between the two images, then slowly brought straight toward the viewer's eyes, keeping the eyes directed at the fingertip; at a certain distance, a fused three-dimensional image should seem to be hovering just above the finger. Alternatively, a piece of paper with a small opening cut into it can be used in a similar manner; when correctly positioned between the image pair and the viewer's eyes, it will seem to frame a small three-dimensional image. Prismatic, self-masking glasses are now being used by some cross-eyed-view advocates. These reduce the degree of convergence required and allow large images to be displayed. However, any viewing aid that uses prisms, mirrors or lenses to assist fusion or focus is simply a type of stereoscope, excluded by the customary definition of freeviewing. Stereoscopically fusing two separate images without the aid of mirrors or prisms while simultaneously keeping them in sharp focus without the aid of suitable viewing lenses inevitably requires an unnatural combination of eye vergence and accommodation. Simple freeviewing therefore cannot accurately reproduce the physiological depth cues of the real-world viewing experience. Different individuals may experience differing degrees of ease and comfort in achieving fusion and good focus, as well as differing tendencies to eye fatigue or strain.

Autostereogram An is a single-image stereogram (SIS), designed to create the visual illusion of a three-dimensional (3D) scene within the human brain from an external two-dimensional image. In order to perceive 3D shapes in these , one must overcome the normally automatic coordination between focusing and vergence.

Stereoscope and stereographic cards The stereoscope is essentially an instrument in which two photographs of the same object, taken from slightly different angles, are simultaneously presented, one to each eye. A simple stereoscope is limited in the size of the image that may be used. A more complex stereoscope uses a pair of horizontal periscope-like devices, allowing the use of larger images that can present more detailed information in a wider field of view.

Transparency viewers

Some are designed for viewing transparent photographs on film or glass, known as transparencies or diapositives and commonly called slides. Some of the earliest stereoscope views, issued in the 1850s, were on glass. In the early 20th century, 45x107 mm and 6x13 cm glass slides were common formats for amateur stereo photography, especially in Europe. In later years, several film-based formats were in use. The best-known formats for commercially issued stereo views on film are Tru-Vue, introduced in 1931, and View-Master, introduced in 1939 and still in production. For amateur stereo slides, the Stereo Realist format, introduced in 1947, is by far the most common. A View-Master Model E of the 1950s Stereoscopy 43

Head-mounted displays

The user typically wears a helmet or glasses with two small LCD or OLED displays with magnifying lenses, one for each eye. The technology can be used to show stereo films, images or games, but it can also be used to create a virtual display. Head-mounted displays may also be coupled with head-tracking devices, allowing the user to "look around" the virtual world by moving their head, eliminating the need for a separate controller. Performing this update quickly enough to avoid inducing nausea in the user requires a great amount of

computer image processing. If six axis position sensing (direction and An HMD with a separate video source displayed position) is used then wearer may move about within the limitations of in front of each eye to achieve a stereoscopic the equipment used. Owing to rapid advancements in computer effect graphics and the continuing miniaturization of video and other equipment these devices are beginning to become available at more reasonable cost.

Head-mounted or wearable glasses may be used to view a see-through image imposed upon the real world view, creating what is called augmented reality. This is done by reflecting the video images through partially reflective mirrors. The real world view is seen through the mirrors' reflective surface. Experimental systems have been used for gaming, where virtual opponents may peek from real windows as a player moves about. This type of system is expected to have wide application in the maintenance of complex systems, as it can give a technician what is effectively "x-ray vision" by combining computer graphics rendering of hidden elements with the technician's natural vision. Additionally, technical data and schematic diagrams may be delivered to this same equipment, eliminating the need to obtain and carry bulky paper documents. Augmented stereoscopic vision is also expected to have applications in surgery, as it allows the combination of radiographic data (CAT scans and MRI imaging) with the surgeon's vision.

Virtual retinal displays A (VRD), also known as a retinal scan display (RSD) or retinal (RP), not to be confused with a "Retina Display", is a display technology that draws a raster image (like a television picture) directly onto the retina of the eye. The user sees what appears to be a conventional display floating in space in front of them. For true stereoscopy, each eye must be provided with its own discrete display. To produce a virtual display that occupies a usefully large visual angle but does not involve the use of relatively large lenses or mirrors, the light source must be very close to the eye. A contact lens incorporating one or more semiconductor light sources is the form most commonly proposed. As of 2013, the inclusion of suitable light-beam-scanning means in a contact lens is still very problematic, as is the alternative of embedding a reasonably transparent array of hundreds of thousands (or millions, for HD resolution) of accurately aligned sources of collimated light. Stereoscopy 44

3D viewers

There are two categories of 3D viewer technology, active and passive. Active viewers have electronics which interact with a display. Passive viewers filter constant streams of binocular input to the appropriate eye.

Active A pair of LC shutter glasses used to view XpanD Shutter systems 3D films. The thick frames conceal the electronics and batteries. A shutter system works by openly presenting the image intended for the left eye while blocking the right eye's view, then presenting the right-eye image while blocking the left eye, and repeating this so rapidly that the interruptions do not interfere with the perceived fusion of the two images into a single 3D image. It generally uses liquid crystal shutter glasses. Each eye's glass contains a liquid crystal layer which has the property of becoming dark when voltage is applied, being otherwise transparent. The glasses are controlled by a timing signal that allows the glasses to alternately darken over one eye, and then the other, in synchronization with the refresh rate of the screen.

RealD circular polarized glasses

Passive

Polarization systems To present stereoscopic pictures, two images are projected superimposed onto the same screen through polarizing filters or presented on a display with polarized filters. For projection, a silver screen is used so that is preserved. The viewer wears low-cost eyeglasses which also contain a pair of opposite polarizing filters. As each filter only passes light which is similarly polarized and blocks the opposite polarized light, each eye only sees one of the images, and the effect is achieved.

Interference filter systems This technique uses specific of red, green, and blue for the right eye, and different wavelengths of red, green, and blue for the left eye. Eyeglasses which filter out the very specific wavelengths allow the wearer to see a full color 3D image. It is also known as spectral comb filtering or wavelength multiplex visualization or super-anaglyph. uses this principle. The Omega 3D/Panavision 3D system has also used an improved version of this technology[16] In June 2012 the Omega 3D/Panavision 3D system was discontinued by DPVO Theatrical, who marketed it on behalf of Panavision, citing ″challenging global economic and 3D market conditions″.[17] Although DPVO dissolved its business operations, Omega Optical continues promoting and selling 3D systems to non-theatrical markets. Omega Optical’s 3D system contains projection filters and 3D glasses. In addition to the passive stereoscopic 3D system, Omega Optical has produced enhanced glasses. The Omega’s red/ anaglyph glasses use complex metal oxide thin film coatings and high quality annealed glass optics. Stereoscopy 45

Color anaglyph systems

Anaglyph 3D is the name given to the stereoscopic 3D effect achieved by means of encoding each eye's image using filters of different (usually chromatically opposite) colors, typically red and cyan. Anaglyph 3D images contain two differently filtered colored images, one for each eye. When viewed through the "color-coded" "anaglyph glasses", each of the two images reaches one eye, revealing an integrated stereoscopic image. The visual cortex of the brain fuses this Anaglyph 3D glasses into perception of a three dimensional scene or composition.

Chromadepth system

The ChromaDepth procedure of American Paper Optics is based on the fact that with a prism, colors are separated by varying degrees. The ChromaDepth eyeglasses contain special view foils, which consist of microscopically small prisms. This causes the image to be translated a certain amount that depends on its color. If one uses a prism foil now ChromaDepth glasses with prism-like film with one eye but not on the other eye, then the two seen pictures – depending upon color – are more or less widely separated. The brain produces the spatial impression from this difference. The advantage of this technology consists above all of the fact that one can regard ChromaDepth pictures also without eyeglasses (thus two-dimensional) problem-free (unlike with two-color anaglyph). However the colors are only limitedly selectable, since they contain the depth information of the picture. If one changes the color of an object, then its observed distance will also be changed.[citation needed]

Pulfrich method

The is based on the phenomenon of the human eye processing images more slowly when there is less light, as when looking through a dark lens. Because the Pulfrich effect depends on motion in a particular direction to instigate the illusion of depth, it is not useful as a general stereoscopic technique. For example, it cannot be used to show a stationary object apparently extending into or out of the screen; similarly, objects moving vertically will not be seen as

moving in depth. Incidental movement of objects will create spurious KMQ stereo prismatic viewer with openKMQ artifacts, and these incidental effects will be seen as artificial depth not plastics extensions related to actual depth in the scene. Stereoscopy 46

Over/under format Stereoscopic viewing is achieved by placing an image pair one above one another. Special viewers are made for over/under format that the right eyesight slightly up and the left eyesight slightly down. The most common one with mirrors is the View Magic. Another with prismatic glasses is the KMQ viewer.[] A recent usage of this technique is the openKMQ project.[]

Other display methods without viewers

Autostereoscopy

Autostereoscopic display technologies use optical components in the display, rather than worn by the user, to enable each eye to see a different image. Because headgear is not required, it is also called "glasses-free 3D". The optics split the images directionally into the viewer's eyes, so the display viewing geometry requires limited head positions that will achieve the stereoscopic effect. Automultiscopic displays provide multiple views of the same scene, rather than just two. Each view is visible from a different range of positions in front of the display. This allows the viewer to move left-right in front of the display and see the correct view from any position. The technology

includes two broad classes of displays: those that use head-tracking to The Nintendo 3DS uses barrier ensure that each of the viewer's two eyes sees a different image on the to display a 3D image. screen, and those that display multiple views so that the display does not need to know where the viewers' eyes are directed. Examples of autostereoscopic displays technology include , , volumetric display, and light field displays.

Holography Laser holography, in its original "pure" form of the photographic transmission hologram, is the only technology yet created which can reproduce an object or scene with such complete realism that the reproduction is visually indistinguishable from the original, given the original lighting conditions. It creates a light field identical to that which emanated from the original scene, with parallax about all axes and a very wide viewing angle. The eye differentially focuses objects at different distances and subject detail is preserved down to the microscopic level. The effect is exactly like looking through a window. Unfortunately, this "pure" form requires the subject to be laser-lit and completely motionless—to within a minor fraction of the wavelength of light—during the photographic exposure, and laser light must be used to properly view the results. Most people have never seen a laser-lit transmission hologram. The types of holograms commonly encountered have seriously compromised image quality so that ordinary white light can be used for viewing, and non-holographic intermediate imaging processes are almost always resorted to, as an alternative to using powerful and hazardous pulsed , when living subjects are photographed. Although the original photographic processes have proven impractical for general use, the combination of computer-generated holograms (CGH) and optoelectronic holographic displays, both under development for many years, has the potential to transform the half-century-old pipe dream of holographic into a reality; so far, however, the large amount of calculation required to generate just one detailed hologram, and the huge bandwidth required to transmit a stream of them, have confined this technology to the research laboratory. Stereoscopy 47

Volumetric displays Volumetric displays use some physical mechanism to display points of light within a volume. Such displays use voxels instead of pixels. Volumetric displays include multiplanar displays, which have multiple display planes stacked up, and rotating panel displays, where a rotating panel sweeps out a volume. Other technologies have been developed to project light dots in the air above a device. An laser is focused on the destination in space, generating a small bubble of plasma which emits visible light.

Integral imaging is an autostereoscopic or multiscopic 3D display, meaning that it displays a 3D image without the use of special glasses on the part of the viewer. It achieves this by placing an array of (similar to a lenticular lens) in front of the image, where each lens looks different depending on viewing angle. Thus rather than displaying a 2D image that looks the same from every direction, it reproduces a 4D light field, creating stereo images that exhibit parallax when the viewer moves.

Wiggle stereography Wiggle stereoscopy is an image display technique achieved by quickly alternating display of left and right sides of a stereogram. Found in animated GIF format on the web. Online examples are visible in the New-York Public Library stereogram collection [18]. The technique is also known as "Piku-Piku".[19]

Stereo photography techniques

Film photography

It is necessary to take two photographs from different horizontal positions to get a true stereoscopic image pair. This can be done with two separate side-by-side cameras; with one camera moved from one position to another between exposures; with one camera and a single exposure by means of an attached mirror or prism arrangement that presents a stereoscopic image pair to the ; or with a incorporating two or more side-by-side lenses.

As part of a wider 3-D craze that swept the US in 1953,

stereoscopic photography enjoyed a surge of popularity and a The Stereo Realist, which defined a new stereo format. The new generation of stereoscopic cameras appeared on the middle lens is for view-finding. market. More compact and convenient than their pre-World War II predecessors, they adopted the increasingly popular (35 mm) format that allowed the use of color film, which produced color transparencies ("slides") instead of prints on paper. The relative novelty of Kodachrome's vivid colors and the realism of 3-D were each attractive individually, but the astonishingly lifelike effect of the two combined proved irresistible to many consumers. The Stereo Realist camera, introduced in 1947, was the pioneer. Already advertised with celebrity endorsements and Stereoscopy 48

well-established when the surge arrived in 1953, it was widely copied but maintained its lead. Its 5P (five film perforations per image) format was adopted as a standard by most of its competitors, including Kodak. The new cameras were marketed with corresponding two-lensed Realist-format slide viewers, which typically had a built-in light source and adjustable optics. With only these two items the owner could capture, relive and share multicolored and stereoscopically preserved memories. For group viewing and perhaps even greater realism, a polarized stereoscopic and silver screen could be added to the system. The popularity of stereoscopic photography waned along with the 1950s 3-D fad, but not so quickly or completely. Subsequent decades found new users replenishing the ranks of loyal devotees, and Sputnik stereo camera (Soviet Union, 1960s). even today, despite the general transition from film to digital and from Although there are three lenses present, only the slide viewing and projection to slide scanning and video display, some lower two are used for the photograph – the third lens serves as a viewfinder for composition. The of this sturdy equipment is still in use by a small core of enthusiasts of Sputnik produces two side-by-side square images all ages. on 120 film.

The 1980s saw a minor revival of stereoscopic photography when several point-and-shoot stereo cameras were introduced. Most of these cameras suffered from poor optics and plastic construction, and were designed to produce lenticular prints, a format which never gained wide acceptance, so they never gained the popularity of the 1950s stereo cameras.

Digital photography The beginning of the 21st century marked the coming of the age of digital photography. Stereo lenses were introduced which could turn an ordinary film camera into a stereo camera by using a special double lens to take two images and direct them through a single lens to capture them side by side on the film. Although current digital stereo cameras cost hundreds of dollars,[20] cheaper models also exist, for example those produced by the company Loreo. It is also possible to create a twin camera rig, together with a "shepherd" device to synchronize the shutter and flash of the two cameras. By mounting two cameras on a bracket, spaced a bit, with a mechanism to make both take pictures at the same time. Newer cameras are even being used to shoot "step video" 3D slide shows with many pictures almost like a 3D motion picture if viewed properly. A modern camera can take ten pictures per second, with images that greatly exceed HDTV resolution. If anything is in motion within the field of view, it is necessary to take both images at once, either through use of a specialized two-lens camera, or by using two identical cameras, operated as close as possible to the same moment. A single camera can also be used if the subject remains perfectly still (such as an object in a museum display). Two exposures are required. The camera can be moved on a sliding bar for offset, or with practice, the photographer can simply shift the camera while holding it straight and level. This method of taking stereo photos is sometimes referred to as the "Cha-Cha" or "Rock and Roll" method.[21] It is also sometimes referred to as the "astronaut shuffle" because it was used to take stereo pictures on the surface of the moon using normal monoscopic equipment.[22] For the most natural looking stereo most move the camera about 65mm or the distance between the eyes,[] but some experiment with other distances. A good rule of thumb is to shift sideways 1/30th of the distance to the closest subject for 'side by side' display, or just 1/60th if the image is to be also used for color anaglyph or anachrome image display. For example, when enhanced depth beyond natural vision is desired and a photo of a person in front of a house is being taken, and the person is thirty feet away, then the camera should be moved 1 foot between shots.[] Stereoscopy 49

The stereo effect is not significantly diminished by slight pan or rotation between images. In fact slight rotation inwards (also called 'toe in') can be beneficial. Bear in mind that both images should show the same objects in the scene (just from different angles) – if a tree is on the edge of one image but out of view in the other image, then it will appear in a ghostly, semi-transparent way to the viewer, which is distracting and uncomfortable. Therefore, the images are cropped so they completely overlap, or the cameras 'toed-in' so that the images completely overlap without having to discard any of the images. However, too much 'toe-in' can cause 'keystoning' and eye strain for reasons best described here.[23]

Digital stereo bases (baselines) There are different cameras with different stereobase (distance between the two camera lenses) in the not professional market of 3D digital cameras used for video and also for stills: 10 mm 3 D Lumix H-FT012 lens (for the GH2, GF2, GF3, GF5 cams and also for the hybrid W8 cam). 12 mm Praktica and Medion 3D (two clones of the DXG-5D8 cam). 20 mm Sony Blogie 3D. 23 mm Loreo 3D Macro lens. 25 mm LG Optimus 3D and LG Optimus 3D MAX smartphones and the close-up macro adapter for the W1 and W3 Fujifilm cams. 28 mm Sharp Aquos SH80F and the Camileo z100 camcorder. 30 mm Panasonic 3D1 camera. 32 mm HTC EVO 3D smartphone. 35 mm JVC TD1, DXG-5G2V and 790 HD (only for anagliph stills and video) camcorders. 40 mm Aiptek I2, Aiptek IS2, Aiptek IH3 and Viewsonic 3D cams. 50 mm Loreo for full frame cams, and the 3D FUN cam of 3dInlife. 55 mm SVP dc-3D-80 cam (parallel & anagliph, stills & video). 60 mm Vivitar 3D cam (only for anagliph pictures. 75 mm Fujifilm W3 cam. 77 mm Fujifilm W1 cam. 88 mm Loreo 3D lens for digital cams. 140mm Cyclopital3D base extender for the JVC TD1 and Sony TD10. 200mm Cyclopital3D base extender for the Panasonic AG-3DA1. 225mm Cyclopital3D base extender for the Fujifilm W1 and W3 cams.

Base line selection

For general purpose stereo photography, where the goal is to duplicate natural human vision and give a visual impression as close as possible to actually being there, the correct baseline (distance between where the right and left images are taken) would be the same as the distance between the eyes.[24] When images taken with such a baseline are viewed using a viewing method that duplicates the conditions under which the picture is taken then the result would be an image pretty much the same as what would be seen at the site the photo was taken. Fujifilm FinePix Real 3D W3 This could be described as "ortho stereo." Stereoscopy 50

An example would be the Realist format that was so popular in the late 1940s to mid-1950s and is still being used by some today. When these images are viewed using high quality viewers, or seen with a properly set up projector, the impression is, indeed, very close to being at the site of photography. The baseline used in such cases will be about 50mm to 80mm. This is what is generally referred to as a "normal" baseline, used in most stereo photography. There are, however, situations where it might be desirable to use a longer or shorter baseline. The factors to consider include the viewing method to be used and the goal in taking the picture. Note that the concept of baseline also applies to other branches of stereography, such as stereo drawings and computer generated stereo images, but it involves the point of view chosen rather than actual physical separation of cameras or lenses.

Longer base line for distant objects "Hyper Stereo" If a stereo picture is taken of a large, distant object such as a mountain or a large building using a normal base it will appear to be flat.[] This is in keeping with normal human vision, it would look flat if one were actually there, but if the object looks flat, there doesn't seem to be any point in taking a stereo picture, as it will simply seem to be behind a stereo window, with no depth in the scene itself, much like looking at a flat photograph from a distance. One way of dealing with this situation is to include a foreground object to add depth interest and enhance the feeling of "being there", and this is the advice commonly given to novice stereographers.[25][26] Caution must be used, however, to ensure that the foreground object is not too prominent, and appears to be a natural part of the scene, otherwise it will seem to become the subject with the distant object being merely the background.[27] In cases like this, if the picture is just one of a series with other pictures showing more dramatic depth, it might make sense just to leave it flat, but behind a window.[27] For making stereo images featuring only a distant object (e.g., a mountain with foothills), the camera positions can be separated by a larger distance (called the "interaxial" or stereo base, often mistakenly called "interocular") than the adult human norm of 62–65mm. This will effectively render the captured image as

though it was seen by a giant, and thus will enhance the Midtown manhattan stereo photograph crosseyed ( ) depth perception of these distant objects, and reduce the apparent scale of the scene proportionately.[28] However, in this case care must be taken not to bring objects in the close foreground too close to the viewer, as they will show excessive parallax and can complicate stereo window adjustment.

There are two main ways to accomplish this. One is to use two cameras separated by the required distance, the Hyperstereo example taken out from airplane while flying over other is to shift a single camera the required distance Greenland and arranged for Crosseyed viewing between shots. The shift method has been used with cameras such as the Stereo Realist to take hypers, either by taking two pairs and selecting the best frames, or by alternately capping each lens and recocking the shutter.[][29] Stereoscopy 51

It is also possible to take hyperstereo pictures using an ordinary single lens camera aiming out an airplane. One must be careful, however, about movement of clouds between shots.[30] It has even been suggested that a version of hyperstereo could be used to help pilots fly planes.[31] In such situations, where an ortho stereo viewing method is used, a common rule of thumb is the 1:30 rule.[32] This means that the baseline will be equal to 1/30 of the distance to the nearest object included in the photograph. The results of hyperstereo can be quite impressive,[33][34][35] and examples of hyperstereo can be found in vintage views.[36] This technique can be applied to 3D imaging of the Moon stereo from 1897 taken using libration. Anaglyph, red left. 3D red cyan glasses are recommended to view this image Moon: one picture is taken at moonrise, the other at correctly. moonset, as the face of the Moon is centered towards the center of the Earth and the diurnal rotation carries the photographer around the perimeter, though the results are rather poor,[37] and much better results can be obtained using alternative techniques.[37]

This is why high quality published stereos of the moon are done using libration,[38][39] [40][41] the slight "wobbling" of the moon on its axis relative to the earth.[42] Similar techniques were used late in the 19th century to take stereo views of Mars and other astronomical subjects.[42]

Limitations of hyperstereo

Vertical alignment can become a big problem, especially if the terrain on which the two camera positions are placed is uneven. Movement of objects in the scene can make syncing two widely separated cameras a nightmare. When a single camera is moved between two positions even subtle movements such as plants blowing in the wind and the movement of clouds can become a problem.[29] The wider the baseline, the more of a problem this becomes.

Pictures taken in this fashion take on the appearance of Illustration of parallax multiplication limits with A at 30 and 2000 a miniature model, taken from a short feet distance,[43][44][45] and those not familiar with such pictures often cannot be convinced that it is the real object. This is because we cannot see depth when looking at such scenes in real life and our brains aren't equipped to deal with the artificial depth created by such techniques, and so our minds tell us it must be a smaller object viewed from a short distance, which would have depth. Though most eventually realize it is, indeed, an image of a large object from far away, many find the effect bothersome.[46] This doesn't rule out using such techniques, but it is one of the factors that need to be considered when deciding whether or not such a technique should be used. Stereoscopy 52

In movies and other forms of "3D" entertainment, hyperstereo may be used to simulate the viewpoint of a giant, with eyes a hundred feet apart. The miniaturization would be just what the photographer (or designer in the case of drawings/computer generated images) had in mind. On the other hand, in the case of a massive ship flying through space the impression that it is a miniature model is probably not what the film makers intended! Hyper stereo can also lead to cardboarding, an effect that creates stereos in which different objects seem well separated in depth, but the objects themselves seem flat. This is because parallax is quantized.[47] Illustration of the limits of parallax multiplication, refer to image at left. Ortho viewing method assumed. The line represents the Z axis, so imagine that it is laying flat and stretching into the distance. If the camera is at X point A is on an object at 30 feet. Point B is on an object at 200 feet and point C is on the same object but 1 inch behind B. Point D is on an object 250 feet away. With a normal baseline point A is clearly in the foreground, with B,C, and D all at stereo infinity. With a one foot base line, which multiplies the parallax, there will be enough parallax to separate all four points, though the depth in the object containing B and C will still be subtle. If this object is the main subject, we may consider a baseline of 6 feet 8 inches but then the object at A would need to be cropped out. Now imagine that the camera is point Y, now the object at A is at 2,000 feet, point B is on an object at 2,170 feet C is a point on the same object 1 inch behind B. Point D is on an object at 2,220 feet. With a normal baseline, all four points are now at stereo infinity. With a 67 foot basline, the multiplied parallax allows us to see that all three objects are on different planes, yet points B and C, on the same object, appear to be on the same plane and all three objects appear flat. This is because there are discrete units of parallax, so at 2,170 feet the parallax between B and C is zero and zero multiplied by any number is still zero.

A practical example

In the red-cyan anaglyph example below, a ten-meter baseline atop the roof ridge of a house was used to image the mountain. The two foothill ridges are about four miles (6.5 km) distant and are separated in depth from each other and the background. The baseline is still too short to resolve the depth of the two more distant major peaks from each other. Owing to various trees that appeared in only one of the images the final image had to be severely cropped at each side and the bottom. In the wider image, taken from a different location, a single camera was walked about one hundred feet (30 m) between pictures. The images were converted to monochrome before combination.(below)

Small anaglyphed image 3D red cyan glasses are recommended to view this image correctly.

Stereoscopy 55

In recent years cameras have been produced which are designed to stereograph subjects 10" to 20" using print film, with a 27mm baseline.[50] Another technique, usable with fixed base cameras such as the Fujifilm FinePix Real 3D W1/W3 is to back off from the subject and use the zoom function to zoom to a closer view, such as was done in the image of a cake. This has the effect of reducing the effective baseline. Similar techniques could be used with paired digital cameras. Another way to take images of very small objects, "extreme macro", is to use an ordinary flatbed scanner. This is a variation on the shift technique in which the object is turned upside down and placed on the scanner, scanned, moved over and scanned again. This produces stereos of a range objects as large as about 6" across down to objects as small as a carrot seed. This technique goes back to at least 1995. See the article for more details. In stereo drawings and computer generated stereo images a smaller than normal baseline may be built into the constructed images to simulate a "bug's eye" view of the scene.

Baseline tailored to viewing method How far the picture is viewed from requires a certain separation between the cameras. This separation is called stereo base or stereo base line and results from the ratio of the distance to the image to the distance between the eyes (usually about 2.5 inches). In any case the farther the screen is viewed from the more the image will pop out. The closer the screen is viewed from the flatter it will appear. Personal anatomical differences can be compensated for by moving closer or farther from the screen. To provide close emulation of natural vision for images viewed on a , a fixed stereo base of 6 cm might be appropriate. This will vary depending on the size of the monitor and the viewing distance. For hyper stereo, a ratio smaller than 1:30 could be used. For example if a stereo image is to be viewed on a computer monitor from a distance of 1000 mm there will be an eye to view ratio of 1000/63 or about 16. To set the cameras the appropriate distance apart for the desired effect, the distance to the subject (say a person at a distance from the cameras of 3 meters) is divided by 16 which yields a stereo base of 188 mm between the cameras. However, images optimized for a small screen viewed from a short distance will show excessive parallax when viewed with more ortho methods, such as a projected image or a head mounted display, possibly causing eyestrain and headaches, or doubling, so pictures optimized for this viewing method may not be usable with other methods. Where images may also be used for anaglyph display a narrower base, say 40mm will allow for less ghosting in the display.

Variable base for "geometric stereo" As mentioned previously, the goal of the photographer may be a reason for using a baseline that is larger than normal. Such is the case when, instead of trying to achieve a close emulation to natural vision, a may be trying to achieve geometric perfection. This approach means that objects are shown with the shape they actually have, rather than the way they are seen by humans. Objects at 25 to 30 feet, instead of having the subtle depth that one being there would see, or what would be recorded with a normal baseline, will have the much more dramatic depth that would be seen from 7 to 10 feet. So instead seeing objects as one would with eyes 2 1/2" apart, they would be seen as they would appear if one's eyes were 12" apart. In other words, the baseline is chosen to produce the same depth effect, regardless of the distance from the subject. As with true ortho, this effect is impossible to achieve in a literal sense, since different objects in the scene will be at different distances and will thus show different amounts of parallax, but the geometric stereographer, like the ortho stereographer attempts to come as close as possible. Achieving this could be as simple as using the 1:30 rule to find a custom base for every shot, regardless of distance, or it could involve using a more complicated formula.[51] Stereoscopy 56

This could be thought of as a form of hyperstereo,[52] but less extreme. As a result, it has all of the same limitations of hyperstereo. When objects are given enhanced depth, but not magnified to take up a larger portion of the view, there is a certain miniaturization effect. Of course, this may be exactly what the stereographer has in mind. While geometric stereo neither attempts nor achieves a close emulation of natural vision, there are valid reasons for this approach. It does, however, represent a very specialized branch of stereography.

Precise stereoscopic baseline calculation methods Recent research has led to precise methods for calculating the stereoscopic camera baseline.[53] These techniques consider the geometry of the display/viewer and scene/camera spaces independently and can be used to reliably calculate a mapping of the scene depth being captured to a comfortable display depth budget. This frees up the photographer to place their camera wherever they wish to achieve the desired composition and then use the baseline calculator to work out the camera inter-axial separation required to produce the desired effect. This approach means there is no guess work in the stereoscopic setup once a small set of parameters have been measured, it can be implemented for photography and computer graphics and the methods can be easily implemented in a software tool.

Multi-rig stereoscopic cameras The precise methods for camera control have also allowed the development of multi-rig stereoscopic cameras where different slices of scene depth are captured using different inter-axial settings,[54] the images of the slices are then composed together to form the final stereoscopic image pair. This allows important regions of a scene to be given better stereoscopic representation while less important regions are assigned less of the depth budget. It provides stereographers with a way to manage composition within the limited depth budget of each individual display technology.

Stereo Window For any branch of stereoscopy the concept of the stereo window is important. If a scene is viewed through a window the entire scene would normally be behind the window, if the scene is distant, it would be some distance behind the window, if it is nearby, it would appear to be just beyond the window. An object smaller than the window itself could even go through the window and appear partially or completely in front of it. The same applies to a part of a larger object that is smaller than the window. The goal of setting the stereo window is to duplicate this effect. To truly understand the concept of window adjustment it is necessary to understand where the stereo window itself is. In the case of projected stereo, including "3D" movies, the window would be the surface of the screen. With printed material the window is at the surface of the paper. When stereo images are seen by looking into a viewer the window is at the position of the frame. In the case of Virtual Reality the window seems to disappear as the scene becomes truly immersive. In the case of paired images, moving the images further apart will move the entire scene back, moving the images closer together will move the scene forward. Note that this does not affect the relative positions of objects within the scene, just their position relative to the window. Similar principles apply to anaglyph images and other stereoscopy techniques. There are several considerations in deciding where to place the scene relative to the window. First, in the case of an actual physical window, the left eye will see less of the left side of the scene and the right eye will see less of the right side of the scene, because the view is partly blocked by the window frame. This principle is known as "less to the left on the left" or 3L, and is often used as a guide when adjusting the stereo window where all objects are to appear behind the window. When the images are moved further apart, the outer edges are cropped by Stereoscopy 57

the same amount, thus duplicating the effect of a window frame. Another consideration involves deciding where individual objects are placed relative to the window. It would be normal for the frame of an actual window to partly overlap or "cut off" an object that is behind the window. Thus an object behind the stereo window might be partly cut off by the frame or side of the stereo window. So the stereo window is often adjusted to place objects cut off by window behind the window. If an object, or part of an object, is not cut off by the window then it could be placed in front of it and the stereo window may be adjusted with this in mind. This effect is how swords, bugs, flashlights, etc. often seem to "come off the screen" in 3D movies. If an object which is cut off by the window is placed in front of it, an effect results that is somewhat unnatural and is usually considered undesirable, this is often called a "window violation". This can best be understood by returning to the analogy of an actual physical window. An object in front of the window would not be cut off by the window frame but would, rather, continue to the right and/or left of it. This can't be duplicated in stereography techniques other than Virtual Reality so the stereo window will normally be adjusted to avoid window violations. There are, however, circumstances where they could be considered permissible. A third consideration is viewing comfort. If the window is adjusted too far back the right and left images of distant parts of the scene may be more than 2.5" apart, requiring that the viewers eyes diverge in order to fuse them. This results in image doubling and/or viewer discomfort. In such cases a compromise is necessary between viewing comfort and the avoidance of window violations. In stereo photography window adjustments is accomplished by shifting/cropping the images, in other form of stereoscopy such as drawings and computer generated images the window is built into the design of the images as they are generated. It is by design that in CGI movies certain images are behind the screen whereas others are in front of it.

Bibliography

Footnotes

[1] στερεός Tufts.edu (http:/ / www. perseus. tufts. edu/ hopper/ text?doc=Perseus:text:1999. 04. 0057:entry=stereo/ s), Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus Digital Library

[2] σκοπέω (http:/ / www. perseus. tufts. edu/ hopper/ text?doc=Perseus:text:1999. 04. 0057:entry=skope/ w), Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus Digital Library [3] Flight Simulation, J. M. Rolfe and K. J. Staples, Cambridge University Press, 1986, page 134 [4] Contributions to the Physiology of Vision.—Part the First. On some remarkable, and hitherto unobserved, Phenomena of Binocular Vision.

By CHARLES WHEATSTONE, F.R.S., Professor of Experimental Philosophy in King's College, London. Stereoscopy.com (http:/ / www.

stereoscopy. com/ library/ wheatstone-paper1838. html) [5][5]Welling, William. Photography in America, page 23 [6] Stereo Realist Manual, p. 375. [7] Stereo Realist Manual, pp. 377–379. [8] Fay Huang, Reinhard Klette, and Karsten Scheibe: Panoramic Imaging (Sensor-Line Cameras and Laser Range-Finders). Wiley & Sons, Chichester, 2008

[13] The Logical Approach to Seeing 3D Pictures (http:/ / www. vision3d. com/ 3views. html). www.vision3d.com by Optometrists Network. Retrieved 2009-08-21

[14] How To Freeview Stereo (3D) Images (http:/ / www. angelfire. com/ ca/ erker/ freeview. html). Greg Erker. Retrieved 2009-08-21

[15] How to View Photos on This Site (http:/ / www. 3dphoto. net/ text/ viewing/ technique. html). Stereo Photography – The World in 3D. Retrieved 2009-08-21 [16][16]"Seeing is believing""; Cinema Technology, Vol 24, No.1 March 2011

[17] http:/ / www. dpvotheatrical. com/

[18] http:/ / stereo. nypl. org/ create

[19] http:/ / www. shortcourses. com/ stereo/ stereo1-17. html [22] Stereo World, National Stereoscopic Association Vol 17 #3 pp. 4–10 [25] Stereo Realist Manual, p. 27. [26] Stereo Realist Manual, p. 261. [27] Stereo Realist Manual, p. 156. Stereoscopy 58

[29][29]Stereo World Volume 37 #1 Inside Front Cover [30][30]Stereoworld Vol 21 #1 March/April 1994 IFC, 51 [31] Stereoworld Vol 16 #1 March/April 1989 pp 36–37 [33] Stereoworld Vol 16 #2 May/June 1989 pp. 20–21 [34] Stereoworld Vol 8 #1 March/April 1981 pp. 16–17 [35] Stereoworld Vol 31 #6 May/June 2006 pp. 16–22 [36] Stereoworld Vol 17 #5 Nov/DEC 1990 pp. 32–33

[37] Stereo Lunar Photos by John C. Ballou (http:/ / home. comcast. net/ ~jlballou/ LunarStereo/ index. html) An in depth looks at moon stereos with examples using several techniques [38] Stereoworld Vol 23 #2 May/June 1996 pp. 25–30

[41] London Stereoscopic Company – Official Web Site (http:/ / www. londonstereo. com/ stereophotography2. html) a more indepth explanation [42] Stereoworld Vol 15 #3 July/August 1988 pp. 25–30 [44] The Vision of Hyperspace, Arthur Chandler, 1975, Stereo World , vol 2 #5 pp. 2–3, 12 [46][46]Hyperspace a comment, Paul Wing, 1976, Stereo World , vol 2 #6 page 2 [48] Willke & Zakowski [49][49]Simmons

References

Sources • Simmons, Gordon (March/April 1996). "Clarence G. Henning: The Man Behind the Macro". Stereo World 23 (1): 37–43. • Willke, Mark A.; Zakowski, Ron (March/April 1996). "A Close Look into the Realist Macro Stereo System". Stereo World 23 (1): 14–35. • Morgan, Willard D.; Lester, Henry M. (October 1954). Stereo Realist Manual. and 14 contributors. New York:

Morgan & Lester. OCLC 789470 (http:/ / www. worldcat. org/ oclc/ 789470).

External links

• Stereoscopy (http:/ / www. dmoz. org/ Arts/ Photography/ Techniques_and_Styles/ 3D/ / ) at the Open Directory Project

• The Quantitative Analysis of Stereoscopic Effect (http:/ / www. vicgi. com/

lenticular-printing-quantitive-analysis. html)

• Durham Visualization Laboratory stereoscopic imaging methods and software tools (http:/ / www. binocularity. org)

• University of Washington Libraries Digital Collections Stereocard Collection (http:/ / content. lib. washington.

edu/ stereoweb/ )

• Stereographic Views of Louisville and Beyond, 1850s–1930 (http:/ / digital. library. louisville. edu/ cdm/

landingpage/ collection/ stereographs/ ) from the University of Louisville Libraries

• Stereoscopy (http:/ / www. flickr. com/ photos/ boston_public_library/ sets/ 72157604192771132/ ) on Flickr

• Extremely rare and detailed Stereoscopic 3D scenes (http:/ / www. panoramio. com/ user/ 63737/ tags/ 3D)

• International Stereoscopic Union (http:/ / www. ISU3D. org)

• 3D STEREO PORTAL Videos & Photos Collection (http:/ / www. 3dstreaming. it) • American University in Cairo Rare Books and Special Collections Digital Library Underwood & Underwood

Egypt Stereoviews Collection (http:/ / digitalcollections. aucegypt. edu/ cdm/ landingpage/ collection/ p15795coll8)

• Views of California and the West, ca. 1867–1903 (http:/ / www. oac. cdlib. org/ findaid/ ark:/ 13030/ tf3489n9sv/ ), The Bancroft Library

• The Ten Commandments of Stereoscopy (http:/ / www. stereoscopynews. com/ download/ software/

923-qthe-ten-commandments-of-stereoscopy. html), article about taking good stereoscopy images (photo and Stereoscopy 59

video)

• Moriarty, Philip. "3D Glasses" (http:/ / www. sixtysymbols. com/ videos/ 3d. htm). Sixty Symbols. Brady Haran for the University of Nottingham. Article Sources and Contributors 60 Article Sources and Contributors

Zone System Source: http://en.wikipedia.org/w/index.php?oldid=564869139 Contributors: Animum, Bhound89, Binksternet, Boneheadmx, Chevreul, Chris the speller, Chris1122, Chris8535, Chrisjohnson, Christoph , Cullen328, Dicklyon, Discpad, Doradus, DragonLord, Dstrehl, Duk, Dziadeck, Eeekster, Exposeitright, Eyesclosed, Fences and windows, Fi9, Flash19901, Fourohfour, GregorB, Grendelkhan, Hertz1888, Hirumon, Hkiahsebag, Hooperbloob, Imroy, Innov8or, Jacopo188, Jcasey130, JeffConrad, Jeremyjgray, Jfpierce, Lambiam, Lik-photo, Lopifalko, Lucassd, Mactographer, Madness, Manamarak, Michael Hardy, Mindmatrix, NathanHawking, Nbarth, Onceuponastar, Poccil, Pol098, Queenvictoria, RJASE1, Racklever, Rogerd, Sander123, Shirtwaist, Snowmonster, Soler97, Someguy1221, Springbk, Srleffler, Ssolomon, SteveHopson, Sweetlew72, Targa86, TedE, Tenebrae, The wub, Thumperward, Tms, Vegaswikian, Ventrilqstman, Vfp15, William Avery, Wolfmofo2754, YUL89YYZ, Yuzerid, 99 anonymous edits

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Contre-jour Source: http://en.wikipedia.org/w/index.php?oldid=563368547 Contributors: 16@r, 83d40m, Al Fecund, Alvesgaspar, Amandajm, Arpingstone, Beyond silence, Bjdehut, Brookie, Cburnett, Centrx, Czar, Encyclopedist, Etan J. Tal, FHy, Heron, Hooperbloob, Howcheng, Imroy, Ioscius, Jjron, John254, KFP, Kappa, Kfasimpaur, Knuckles, Lemon-s, Leonardo Boiko, Lukeroberts, Mactographer, Mercy11, Mheger, MisfitToys, Nbarth, Nono64, Ppntori, Qfl247, Ralf Roletschek, Redquark, Robert Weemeyer, Robofish, SKPhoton, Shyam, SlaveToTheWage, Srtxg, Stephen C. Carlson, Tem42, TenOfAllTrades, Tomer T, Vikreykja, Xaque, Zundark, 12 anonymous edits

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Pinhole camera Source: http://en.wikipedia.org/w/index.php?oldid=566370761 Contributors: 09swild, 14chongce1, 842U, Ada shen, AddressOk, Alan Liefting, Aljays, AllanX, Alphachimp, Alsaker, AlternativePhotography, Amatulic, Amble, Anna Lincoln, Apokryltaros, Arniep, Art Carlson, Art LaPella, Artlondon, Arturobandini, Astaykov2, AwamerT, Baffle gab1978, Bansp, Barek, Barneca, BenFrantzDale, BigPimpinBrah, Bjdehut, Bobblewik, Bobo192, Bongwarrior, Booksworm, BorgQueen, Braincricket, Brandon5485, Brion VIBBER, Buybooks Marius, C.uzum, Can't sleep, clown will eat me, Canadian-Bacon, Capricorn42, Carcharoth, Cbaer, Cchriste, CharlesHBennett, ChrisHodgesUK, Christopherlin, Ciphers, Cjs2111, Cmglee, Cnetra, CommonsDelinker, CompactFish, Crazysane, Cremepuff222, Cskirksey, Cst17, DVdm, Dancter, Danner578, Danski14, Dav2008, Dave souza, Davewho2, David Martland, Davidgutschick, Deltabeignet, Deor, DerHexer, Dicklyon, Discospinster, Dobs, Dojo 19, Douglas Whitaker, DrBob, Ds13, Duchamp, Egil, Eivind F Øyangen, ElKevbo, Elizgoiri, Epbr123, Epitalon, Erianna, Ericd, Erik Kennedy, EscapingLife, EvelinaB, Ewan McGregor, Excirial, Falcon8765, Firestarter001, Fourohfour, Frango com Nata, Freakofnurture, Freshacconci, Gadfium, Gail, Geni, Giftlab, Gilliam, Gingersnaps02689, Glane23, Glenn, Googleplex12, Gpeterw, Guanaco55, H005, Habib Muradov, Hambergerhead, HamburgerRadio, Heimstern, Hooperbloob, Horkana, ITEsafety, Imnotminkus, Imroy, Isarra (HG), J.delanoy, J8079s, JJ Harrison, Jadedoto, Jagged 85, JohnClarknew, Joseph Solis in Australia, KYN, Kate, Kazikameuk, Kencf0618, Khateeb88, Klilidiplomus, Kristoffersson, Kurt Eichenberger, Kwamikagami, LOL, Lacomba, Larry laptop, Leafyplant, Mactographer, Mandarax, MarcM1098, MarkSweep, Martarius, Martijn Witlox, Materialscientist, Mato, Mcyccc, Merovingian, Mindmatrix, Minna Sora no Shita, Mmarkon, Mooglemoogle, Mpetrizzo, Mr Stephen, Mr. Stradivarius, MrBenn, MrOllie, Mstahl, Muua3, Mysidia, NawlinWiki, Nbreslin, Nicolai g, Nonexistant User, NoodleWhacks, Numbermaniac, Nyttend, Olivier, Osman09, Oxymoron83, Paddles, Pawyilee, Pbroks13, Peppergrower, PericlesofAthens, Petero9, Phiarc, Phil Gee, Philthecow, Pieter Kuiper, PlanetStar, Poetaris, Professorjohnas, Pscott558, Pustelnik, Pyrospirit, Qqqee, R'n'B, Raghav96, RainbowOfLight, Ratherbeinsane, Rc3784, Reach Out to the Truth, Reatlas, RedWolf, Redbobblehat, Rettetast, RexNL, Rich Farmbrough, Rjwilmsi, Rostayob, Rror, Sam Hocevar, Sam Korn, Sanbeg, Sapata, Sardanaphalus, Schwallex, Sean William, Secret (renamed), Sg227, ShakingSpirit, Shanes, Shanmugamp7, Sho Uemura, SimonD, SkerHawx, Slakr, Smurfoid, Snodfrey, Socrates2008, SonicAD, Spacepotato, SpellChecker, Srleffler, Stephenb, Strice, Stroumphette, Sulfis, Sven Korsgaard, Syncategoremata, The Quirky Kitty, The Thing That Should Not Be, Theda, Thegreenj, Themaskobscure, Thingg, Three, Tinss, Tobias Bergemann, Toghome, Triona, Tweek, Txomin, Tyrenius, Van der Hoorn, Velella, Very little gravitas indeed, Violinist67, Vrenator, Wandering Ghost, Webclient101, Wik, WikiDao, Wile E. Article Sources and Contributors 61

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Brackets, User A1, Uvaphdman, Vailads, Vanished user uih38riiw4hjlsd, Vasily-Vasily, Vaynamar, Verne Equinox, Vilerage, ViperSnake151, Vkil, Voidxor, Volkan Y, Volkan Yuksel, Vossman, Vrenator, Vybr8, WVhybrid, Wagino 20100516, Wayne Gloege, Webmoof, Who, Wiaijk, Wik, Wiki-user-lsw, Wiki13, WikiSlasher, Wikibarista, Wikipedian2, Willsiv, Windward1, Wintonian, Wittkowsky, Wm, Woohookitty, Wuhwuzdat, anonymous edits 588 ,ﻭﺍﮊﻩ ﯾﺎﺩ ,X-Fi6, Xaa, Xavier Giró, Xenonice, Xenophon777, Xnn, Xorx77, Xyoureyes, Zanimum, Zigger, Zolikk Image Sources, Licenses and Contributors 62 Image Sources, Licenses and Contributors

File:ZoneSystem-Gradient.png Source: http://en.wikipedia.org/w/index.php?title=File:ZoneSystem-Gradient.png License: GNU Free Documentation License Contributors: Original uploader was Imroy at en.wikipedia File:ZoneSystem-Gradient-lines.png Source: http://en.wikipedia.org/w/index.php?title=File:ZoneSystem-Gradient-lines.png License: GNU Free Documentation License Contributors: Original uploader was Imroy at en.wikipedia File:.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Redscale.jpg License: Public Domain Contributors: SirJello37 File:BrnoSunsetHDRExampleByIgor.jpg Source: http://en.wikipedia.org/w/index.php?title=File:BrnoSunsetHDRExampleByIgor.jpg License: Creative Commons Attribution-Share Alike Contributors: Igor Iric, Igor Irić, Игор Ирић, File:Leuk01.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Leuk01.jpg License: Creative Commons Attribution 2.0 Contributors: Wolfgang Staudt from Saarbruecken, Germany File:HDR image + 3 source pictures (Cerro Tronador, Argentina).jpg Source: http://en.wikipedia.org/w/index.php?title=File:HDR_image_+_3_source_pictures_(Cerro_Tronador,_Argentina).jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: Mariano Szklanny Image:New York City at night HDR edit1.jpg Source: http://en.wikipedia.org/w/index.php?title=File:New_York_City_at_night_HDR_edit1.jpg License: Creative Commons Attribution-Sharealike 2.0 Contributors: Paulo Barcellos Jr. File:LeGray brick.jpg Source: http://en.wikipedia.org/w/index.php?title=File:LeGray_brick.jpg License: Public Domain Contributors: Jarekt, Yann File:Nuvola apps kview.svg Source: http://en.wikipedia.org/w/index.php?title=File:Nuvola_apps_kview.svg License: unknown Contributors: Ch1902, Saibo file:Searchtool.svg Source: http://en.wikipedia.org/w/index.php?title=File:Searchtool.svg License: GNU Lesser General Public License Contributors: Anomie File:Wyckoff HDR Curve.tif Source: http://en.wikipedia.org/w/index.php?title=File:Wyckoff_HDR_Curve.tif License: unknown Contributors: SteveMcCluskey Image:StLouisArchMultExpEV-4.72.JPG Source: http://en.wikipedia.org/w/index.php?title=File:StLouisArchMultExpEV-4.72.JPG License: Creative Commons Attribution-Sharealike 3.0 Contributors: Kevin McCoy Image:StLouisArchMultExpEV-1.82.JPG Source: http://en.wikipedia.org/w/index.php?title=File:StLouisArchMultExpEV-1.82.JPG License: Creative Commons Attribution-Sharealike 3.0 Contributors: Kevin McCoy Image:StLouisArchMultExpEV+1.51.JPG Source: http://en.wikipedia.org/w/index.php?title=File:StLouisArchMultExpEV+1.51.JPG License: Creative Commons Attribution-Sharealike 3.0 Contributors: Kevin McCoy Image:StLouisArchMultExpEV+4.09.JPG Source: http://en.wikipedia.org/w/index.php?title=File:StLouisArchMultExpEV+4.09.JPG License: Creative Commons Attribution-Sharealike 3.0 Contributors: Kevin McCoy File:StLouisArchMultExpCDR.jpg Source: http://en.wikipedia.org/w/index.php?title=File:StLouisArchMultExpCDR.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: StLouisArchMultExpEV-4.72.JPG: Kevin McCoy StLouisArchMultExpEV-1.82.JPG: Kevin McCoy StLouisArchMultExpEV+1.51.JPG: Kevin McCoy StLouisArchMultExpEV+4.09.JPG: Kevin McCoy derivative work: Darxus (talk) File:StLouisArchMultExpToneMapped.jpg Source: http://en.wikipedia.org/w/index.php?title=File:StLouisArchMultExpToneMapped.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: StLouisArchMultExpEV-4.72.JPG: Kevin McCoy StLouisArchMultExpEV-1.82.JPG: Kevin McCoy StLouisArchMultExpEV+1.51.JPG: Kevin McCoy StLouisArchMultExpEV+4.09.JPG: Kevin McCoy derivative work: Darxus (talk) Image:The Sound of Silence +2EV.jpg Source: http://en.wikipedia.org/w/index.php?title=File:The_Sound_of_Silence_+2EV.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:Neptune8907 Image:The Sound of Silence -2EV.jpg Source: http://en.wikipedia.org/w/index.php?title=File:The_Sound_of_Silence_-2EV.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:Neptune8907 File:The Sound of Silence Resulting HDR.jpg Source: http://en.wikipedia.org/w/index.php?title=File:The_Sound_of_Silence_Resulting_HDR.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:Neptune8907 Image:Al Qasba.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Al_Qasba.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:Ferozeea Image:Trencin hdr 001.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Trencin_hdr_001.jpg License: Creative Commons Attribution 3.0 Contributors: Abphoto Image:Charles River 2 (Pear Biter).jpg Source: http://en.wikipedia.org/w/index.php?title=File:Charles_River_2_(Pear_Biter).jpg License: Creative Commons Attribution-Sharealike 2.0 Contributors: Eric Hill from Boston, MA, USA Image:CoucherDeSoleilLaGarde.jpg Source: http://en.wikipedia.org/w/index.php?title=File:CoucherDeSoleilLaGarde.jpg License: Creative Commons Attribution-Sharealike 3.0,2.5,2.0,1.0 Contributors: Philippe Cosentino Image:DusseldorfOldPort.jpg Source: http://en.wikipedia.org/w/index.php?title=File:DusseldorfOldPort.jpg License: Creative Commons Attribution 2.0 Contributors: Jo Schmaltz from Hongkong, Hongkong Image:Goztepe Park 06773.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Goztepe_Park_06773.jpg License: GNU Free Documentation License Contributors: Nevit Dilmen Image:Hackerbrücke Sonnenuntergang.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Hackerbrücke_Sonnenuntergang.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: Richard Huber Image:Grand Hotel, Lund-1.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Grand_Hotel,_Lund-1.jpg License: Public Domain Contributors: ComputerHotline, Darwinius, Dcastor, H005, Mattes Image:Kobrin suvoros st..jpg Source: http://en.wikipedia.org/w/index.php?title=File:Kobrin_suvoros_st..jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:Askad.skynet Image:Skadovsk sunset.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Skadovsk_sunset.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:Askad.skynet Image:HDR The sound of silence (The road to Kamakhya).jpg Source: http://en.wikipedia.org/w/index.php?title=File:HDR_The_sound_of_silence_(The_road_to_Kamakhya).jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:Neptune8907 Image:View from the Dandenongs in winter.jpg Source: http://en.wikipedia.org/w/index.php?title=File:View_from_the_Dandenongs_in_winter.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:Peter Campbell file:Contre jour, Queenscliff, jjron, 05.12.2009.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Contre_jour,_Queenscliff,_jjron,_05.12.2009.jpg License: GNU Free Documentation License Contributors: jjron file:The Photographer.jpg Source: http://en.wikipedia.org/w/index.php?title=File:The_Photographer.jpg License: Creative Commons Attribution-ShareAlike 3.0 Unported Contributors: Joaquim Alves Gaspar File:Night Photography.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Night_Photography.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: www.modernartphotograph.com Portland Photographer Robert Knapp File:Singapore Skyline Raffles Place.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Singapore_Skyline_Raffles_Place.jpg License: Creative Commons Attribution-ShareAlike 3.0 Unported Contributors: Image by Calvin Teo (User:Advanced) File:Top of Jebel Hafeet.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Top_of_Jebel_Hafeet.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:Xalan mustafa File:Nyc10795u.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Nyc10795u.jpg License: Public Domain Contributors: Berrucomons, Jmabel, Simonizer, Thierry Caro, Trialsanderrors File:Chay kenar - Tabriz.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Chay_kenar_-_Tabriz.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:Jacopo188 File:Subhash Marg in Indore, India.JPG Source: http://en.wikipedia.org/w/index.php?title=File:Subhash_Marg_in_Indore,_India.JPG License: Creative Commons Attribution-ShareAlike 3.0 Unported Contributors: Kprateek88 Image Sources, Licenses and Contributors 63

File:Sydney Opera House - Dec 2008.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Sydney_Opera_House_-_Dec_2008.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: Diliff Image:Bay Bridge at night by Mikl Barton.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Bay_Bridge_at_night_by_Mikl_Barton.jpg License: Creative Commons Attribution 3.0 Contributors: Mikl Barton Image:Picture 121.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Picture_121.jpg License: Creative Commons Attribution-ShareAlike 3.0 Unported Contributors: Adrignola, Look2See1, Morio, Picturetokyo, Ronaldino, Vantey Image:Example of night photography at The Garden of Five Senses, New Delhi.JPG Source: http://en.wikipedia.org/w/index.php?title=File:Example_of_night_photography_at_The_Garden_of_Five_Senses,_New_Delhi.JPG License: Creative Commons Attribution-ShareAlike 3.0 Unported Contributors: Kprateek88 Image:Carnival wikipedia.JPG Source: http://en.wikipedia.org/w/index.php?title=File:Carnival_wikipedia.JPG License: GNU Free Documentation License Contributors: Theviewlv, 2 anonymous edits Image:WashingtonParkBlossomingTree.jpg Source: http://en.wikipedia.org/w/index.php?title=File:WashingtonParkBlossomingTree.jpg License: Public Domain Contributors: Self. Image:WTC Twin Towers Night July 2001.jpg Source: http://en.wikipedia.org/w/index.php?title=File:WTC_Twin_Towers_Night_July_2001.jpg License: Creative Commons Attribution-Sharealike 2.0 Contributors: Filipe Fortes from New York, United States File:Ggb by night.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Ggb_by_night.jpg License: GNU Free Documentation License Contributors: Image taken by Daniel Schwen Image:Taipei 101 at night.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Taipei_101_at_night.jpg License: GNU Free Documentation License Contributors: Meow Image:STS-109 launch.jpg Source: http://en.wikipedia.org/w/index.php?title=File:STS-109_launch.jpg License: Public Domain Contributors: NASA Image:TorontoHTOPark5.jpg Source: http://en.wikipedia.org/w/index.php?title=File:TorontoHTOPark5.jpg License: Public Domain Contributors: Raysonho @ Open Grid Scheduler / Grid Engine File:HMAS Onslow-.jpg Source: http://en.wikipedia.org/w/index.php?title=File:HMAS_Onslow-.jpg License: Creative Commons Attribution-Sharealike 2.5 Contributors: Adam.J.W.C. Image:(1) UNSW entrance a2.JPG Source: http://en.wikipedia.org/w/index.php?title=File:(1)_UNSW_entrance_a2.JPG License: GNU Free Documentation License Contributors: Orestes654 (talk) 08:57, 3 December 2010 (UTC) File:Copenhagen at night.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Copenhagen_at_night.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: Roei.tabak Image:Lunar-eclipse-2004.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Lunar-eclipse-2004.jpg License: GNU Free Documentation License Contributors: Original uploader was Mactographer at en.wikipedia (Original text : David Ball) File:Karlheinz Stockhausen par Claude Truong-Ngoc 1980.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Karlheinz_Stockhausen_par_Claude_Truong-Ngoc_1980.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:Ctruongngoc File:Neon Cowboy Sunset double exposure.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Neon_Cowboy_Sunset_double_exposure.jpg License: Creative Commons Attribution 2.0 Contributors: Cameron Russell from AUSTIN, TX, USA File:Multiexposer of 7 person using adobe photoshop new.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Multiexposer_of_7_person_using_adobe_photoshop_new.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: Janendra Image:UndigitalD2h.jpg Source: http://en.wikipedia.org/w/index.php?title=File:UndigitalD2h.jpg License: GNU Free Documentation License Contributors: Glogger, 1 anonymous edits Image:Camera obscura box.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Camera_obscura_box.jpg License: GNU Free Documentation License Contributors: Che, Draceane, Stigmj, Wutsje, Zhuyifei1999, 3 anonymous edits File:Camerae-obscurae.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Camerae-obscurae.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: Edal Anton Lefterov File:Camera obscura Prague.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Camera_obscura_Prague.jpg License: Creative Commons Attribution 3.0 Contributors: Gampe Image:Camera obscura.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Camera_obscura.jpg License: Public Domain Contributors: Augiasstallputzer, Conscious, Foma39, Jodo, Lars Washington, Ma-Lik, Maksim, 1 anonymous edits File:Camera obscura2.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Camera_obscura2.jpg License: Public Domain Contributors: unknown, possibly Italian File:Canaletto4fogli.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Canaletto4fogli.jpg License: Public Domain Contributors: clop Image:CameraObscura.JPG Source: http://en.wikipedia.org/w/index.php?title=File:CameraObscura.JPG License: Public Domain Contributors: Seth_Ilys (talk) (Uploads). Original uploader was Seth Ilys at en.wikipedia Image:CameraObscuraSanFranciscoCliffHouse.jpg Source: http://en.wikipedia.org/w/index.php?title=File:CameraObscuraSanFranciscoCliffHouse.jpg License: GNU Free Documentation License Contributors: Ioerror, Shyam Image:Camara-obscura-image.JPG Source: http://en.wikipedia.org/w/index.php?title=File:Camara-obscura-image.JPG License: Public Domain Contributors: Code6840 Image:Camera Obscura.JPG Source: http://en.wikipedia.org/w/index.php?title=File:Camera_Obscura.JPG License: Creative Commons Attribution-Sharealike 3.0 Contributors: Saraplacid Image:Camera_Obscura_box18thCentury.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Camera_Obscura_box18thCentury.jpg License: Public Domain Contributors: unknown illustrator Image:Modern Camera Obscura.JPG Source: http://en.wikipedia.org/w/index.php?title=File:Modern_Camera_Obscura.JPG License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:The Bearded Man Image:Camera Obscura in Use.JPG Source: http://en.wikipedia.org/w/index.php?title=File:Camera_Obscura_in_Use.JPG License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:The Bearded Man File:Pinhole-camera.svg Source: http://en.wikipedia.org/w/index.php?title=File:Pinhole-camera.svg License: Public Domain Contributors: en:User:DrBob (original); en:User:Pbroks13 (redraw) File:IMG 1650 zonsverduistering Malta.JPG Source: http://en.wikipedia.org/w/index.php?title=File:IMG_1650_zonsverduistering_Malta.JPG License: GNU Free Documentation License Contributors: User:Ellywa File:PinholeCameraAndRelatedSupplies.jpg Source: http://en.wikipedia.org/w/index.php?title=File:PinholeCameraAndRelatedSupplies.jpg License: Creative Commons Attribution-Sharealike 2.5 Contributors: Douglas Whitaker, Miquonranger03, 1 anonymous edits File:Schießscharten als Lochkamera.JPG Source: http://en.wikipedia.org/w/index.php?title=File:Schießscharten_als_Lochkamera.JPG License: Creative Commons Attribution-Sharealike 3.0,2.5,2.0,1.0 Contributors: H005 File:LongExposurePinhole.jpg Source: http://en.wikipedia.org/w/index.php?title=File:LongExposurePinhole.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: Ewan McGregor File:PinholeCameraImage.jpg Source: http://en.wikipedia.org/w/index.php?title=File:PinholeCameraImage.jpg License: Public Domain Contributors: Willspear1564 File:Pinhole Photographs.JPG Source: http://en.wikipedia.org/w/index.php?title=File:Pinhole_Photographs.JPG License: Public domain Contributors: 32bitmaschine, Conscious, JeremyA, Maksim, Pierpao, 3 anonymous edits File:PinholeCameraCloseup.jpg Source: http://en.wikipedia.org/w/index.php?title=File:PinholeCameraCloseup.jpg License: Creative Commons Attribution-Sharealike 2.5 Contributors: Bkell, Douglas Whitaker, 2 anonymous edits File:Pinhole hydrant neg pos.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Pinhole_hydrant_neg_pos.jpg License: Creative Commons Attribution-Sharealike 2.5 Contributors: Matthew Clemente File:Pocket stereoscope.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Pocket_stereoscope.jpg License: Creative Commons Attribution-ShareAlike 3.0 Unported Contributors: Joaquim Alves Gaspar File:Charles Street Mall, Boston Common, by Soule, John P., 1827-1904 3.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Charles_Street_Mall,_Boston_Common,_by_Soule,_John_P.,_1827-1904_3.jpg License: Public Domain Contributors: M2545 File:August Fuhrmann-Kaiserpanorama 1880.jpg Source: http://en.wikipedia.org/w/index.php?title=File:August_Fuhrmann-Kaiserpanorama_1880.jpg License: Public Domain Contributors: unknown, Original uploader was Nieborak at pl.wikipedia Image Sources, Licenses and Contributors 64

File:Company of ladies watching stereoscopic photographs by Jacob Spoel 1820-1868.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Company_of_ladies_watching_stereoscopic_photographs_by_Jacob_Spoel_1820-1868.jpg License: Public Domain Contributors: Infrogmation, Jan Arkesteijn, KTo288, Vincent Steenberg, 1 anonymous edits Image:Charles Wheatstone-mirror stereoscope XIXc.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Charles_Wheatstone-mirror_stereoscope_XIXc.jpg License: Public Domain Contributors: Original uploader was Nieborak at pl.wikipedia File:Early bird stereograph2.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Early_bird_stereograph2.jpg License: Public Domain Contributors: E.R. McCollister Image:3dviewer. Source: http://en.wikipedia.org/w/index.php?title=File:3dviewer.gif License: Creative Commons Attribution-Share Alike Contributors: Samu3d David Samuel File:View-Master Model E.JPG Source: http://en.wikipedia.org/w/index.php?title=File:View-Master_Model_E.JPG License: Creative Commons Attribution-Sharealike 3.0 Contributors: ThePassenger Image:EmaginZ800.jpg Source: http://en.wikipedia.org/w/index.php?title=File:EmaginZ800.jpg License: GNU Free Documentation License Contributors: User Psoreilly on en.wikipedia File:Xpand LCD shutter glasses.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Xpand_LCD_shutter_glasses.jpg License: Creative Commons Attribution-Sharealike 3.0 Contributors: Original uploader was Amidror1973 at en.wikipedia File:REALD.JPG Source: http://en.wikipedia.org/w/index.php?title=File:REALD.JPG License: Public Domain Contributors: Midori iro File:Anaglyph glasses.png Source: http://en.wikipedia.org/w/index.php?title=File:Anaglyph_glasses.png License: Creative Commons Attribution-ShareAlike 3.0 Unported Contributors: Snaily File:Farbfilterbrille mit Minilinsen.png Source: http://en.wikipedia.org/w/index.php?title=File:Farbfilterbrille_mit_Minilinsen.png License: GNU Free Documentation License Contributors: Stefan Kühn Original uploader was Stefan Kühn at de.wikipedia Image:Bild-OpenKMQKit1.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Bild-OpenKMQKit1.jpg License: Public domain Contributors: Thomas Kumlehn File:Nintendo-3DS-AquaOpen.png Source: http://en.wikipedia.org/w/index.php?title=File:Nintendo-3DS-AquaOpen.png License: Public Domain Contributors: Evan-Amos Image:Stereo Realist.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Stereo_Realist.jpg License: Creative Commons Attribution-Sharealike 2.5 Contributors: Kim Scarborough File:Sputnik stereo camera.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Sputnik_stereo_camera.jpg License: Creative Commons Attribution 3.0 Contributors: Bilby Image:Fujiw3.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Fujiw3.jpg License: Creative Commons Attribution-Share Alike Contributors: John Alan Elson Image:Stereogram guide cross-eyed.png Source: http://en.wikipedia.org/w/index.php?title=File:Stereogram_guide_cross-eyed.png License: Creative Commons Attribution-Sharealike 3.0 Contributors: Hyacinth File:Stereo empire.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Stereo_empire.jpg License: Creative Commons Attribution 3.0 Contributors: User:El pak File:Sterescopic image of Greenland X-3D by Volkan Yuksel DSC05293.JPG Source: http://en.wikipedia.org/w/index.php?title=File:Sterescopic_image_of_Greenland_X-3D_by_Volkan_Yuksel_DSC05293.JPG License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:Volkan Yuksel file:3d glasses red cyan.svg Source: http://en.wikipedia.org/w/index.php?title=File:3d_glasses_red_cyan.svg License: Creative Commons Attribution-Sharealike 2.5 Contributors: Image created using Inkscape by Daniel Schwen. Image:Moonstereo1897.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Moonstereo1897.jpg License: Public Domain Contributors: Scanned by John Alan Elson Image:Parlimit.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Parlimit.jpg License: Creative Commons Attribution-Share Alike Contributors: John Alan Elson Image:LBMtDiabloclip.jpg Source: http://en.wikipedia.org/w/index.php?title=File:LBMtDiabloclip.jpg License: Creative Commons ShareAlike 1.0 Generic Contributors: Original uploader was Leonard G. at en.wikipedia Image:LBLFoothillsBWAna.jpg Source: http://en.wikipedia.org/w/index.php?title=File:LBLFoothillsBWAna.jpg License: Creative Commons ShareAlike 1.0 Generic Contributors: Mdd4696, Mercurywoodrose, Schieber, Speck-Made Image:Stereogram guide parallel.png Source: http://en.wikipedia.org/w/index.php?title=File:Stereogram_guide_parallel.png License: Public Domain Contributors: Hyacinth Image:Wavellite3d.jpg Source: http://en.wikipedia.org/w/index.php?title=File:Wavellite3d.jpg License: Creative Commons Attribution-Share Alike Contributors: John Alan Elson License 65 License

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