Moscow state university

Faculty of Computational MathematicMathematicss and Cybernetics

Digital

Strjelbitskaja Maria, Moscow, 2009

Contents

1 History

2 Sensors and storage

3 Multifunctionality and connectivity

4 Performance metrics

4.1 counts

4.2 Resolution

5

6 Applications and considerations

7 Sensor size and

8 Storage

9 Digital backs

10 Comparison with film photography

10.1 Advantages of consumer digital

10.2 Advantages of professional digital cameras

10.3 Disadvantages of digital cameras

10.4 Equivalent features

10.5 A comparison of frame aspect ratios

11 Market impact

12 Social impact

13 Recent research and innovation

Digital photography

Digital photographotographyphy is a form of photography that utilizes digital technologytechnology to make images of subjects. Until the advent of such technology, photography used to create imimageagess whicich wh h could could be made made visibl visiblee by photog photograpraphichic proces processinsing.g. By contrtrast con ast,, digitaitall dig can be displayed, printed, stored, manipulated, transmitted, and archived using digital and computer techniques, without chemical processing.

non-non-photDigitalphotogra photographyographicphic equipme equi is onepment ofnt severalsuch asforms computer comp ofuter digi taltomogra tom imaging.ographyphy Digital scanners scanners images and are radio radi alsoo telescop telecreatedscopes. byes. Digital images can also be made by scanning conventional photographic images.

History Early development The concept of digitizing images on scanners, and the concept of digitizing video signals, predate the concept of making still pictures by digitizing signals from an array of discrete sensor elements. Eugene F. Lally of the Jet Propulsion Laboratory published the first description of how to produce still photos in a digital domain using a mosaic photosensor. The purpose was to provide onboard navigation information to astronauts during missions to planets. The mosaic array periodically recorded still photos of star and planet locations during transit and when apprapproachoachinging a planet planet provided provided addition additionalal stadiame stadiametrictric informat informationion for orbiting orbiting and landing landing guidance. The concept included camera design elements foreshadowing the first . Texas Instruments engineer Willis Adcock designed a filmless camera and applied for a patent in 1972, but it is not known whether it was ever built. The first recorded attempt at building a digital camera was in 1975 by Steven Sasson, an engineer at Eastman . It used the then- new solid-state CCD chips developed by Fairchild Semiconductor in 1973. The camera weighed 8 pounds (3.6 kg), recorded images to a cassette tape, had a resolution of 0.01 megapixels (10,000 ), and took 23 seconds to capture its first image in December 1975. The prototype camera was a technical exercise, not intended for production.

Analog electronic cameras Handheld electronic cameras, in the sense of a device meant to be carried and used like a handheld film camera, appeared in 1981 with the demonstration of the Sony Mavica (Magnetic Video Camera). This is not to be confused with the later cameras by Sony that also bore the Mavica name. This was an analog camera, in that it recorded pixel signals continuously, as videotape machines did, without converting them to discrete levels; it recorded television-like signals to a 2 × 2 inch "video floppy". In essence it was a video that recorded single frames, 50 per disk in field mode and 25 per disk in frame mode. The image quality was considered equal to that of then-current televisions. Analog electronic cameras do not appear to have reached the market until 1986 with the Canon RC-701. Canon demonstrademonstratedted a prototypeprototype of this model at the 1984 SummerSummer Olympics, printing the images in the Yomiuri Shimbun, a Japanese newspaper. In the United States, the first publication to use these cameras for real reportage was USA Today, in its coverage of World Series baseball. Several factors held back the widespread adoption of analog cameras; the cost (upwards of $20,000), poor image quality compared to film, and the lack of quality affordable printers. Capturing and printing an image originally required access to equipment such as a frame grabber, which was beyond the reach of the average consumer. The "video floppy" disks later had several reader devices available for viewing on a screen, but were never standardized as a computer drive. The early adopters tended to be in the news media, where the cost was negated by the utilityutility and the ability to transmit images by telephone lines. The poor image quality was offset by the low

resolutioresolutionn of newspapernewspaper graphics. This capability to transmittransmit images without a satellite link was useful during the Tiananmen Square protests of 1989 and the first Gulf War in 1991. US government agencies also took a strong interest in the still video concept, notably the US Navy for use as a real time air-to-sea surveillance system. The first analog camera marketed to consumers may have been the Canon RC-250 Xapshot in 1988. A notable analog camera produced the same year was the QV-1000C, designed as a and not offered for sale to general users, which sold only a few hundred units. It recorded images in greyscale, and the quality in newspaper print was equal to film cameras. In appearance it closely resembled a modern digital single-lens reflex camera. Images were stored on video floppy disks.

The arrival of true digital cameras The first true digital camera that recorded images as a computerized file was likely the Fuji DS- 1P of 1988, which recorded to a 16 MB internal memory card that used a battery to keep the data in memory. This camera was never marketed in the United States, and has not been confirmed to have shipped even in Japan. The first commercially available digital camera was the 1990 Dycam Model 1; it also sold as the Logitech Fotoman. It used a CCD image sensor, stored pictures digitally, and connected directly to a computer for download. In 1991, Kodak brought to market the Kodak DCS-100, the beginning of a long line of professional SLR cameras by Kodak that were based in part on film bodies, often . It used a 1.3 megapixel sensor and was priced at $13,000.

inThe 1988, move which to digital allowed formats image was and helped video by files the toforma be compressedtion of the first for storage.JPEG and The MPEG first consumer standards camera with a liquid crystal display on the back was the Casio QV-10 in 1995, and the first camera to use CompactFlash was the Kodak DC-25 in 1996.

The marketplace for consumer digital cameras was originally low resolution (either analog or digidigital)tal) camerascameras built built for utility utility.. In 1997 the firfirstst megapix megapixelel cameras cameras for consume consumersrs weree wer marketed. The first camera that offered the ability to record video clips may have been the Ricoh RDC-1 in 1995. 1999 saw the introduction of the Nikon D1, a 2.74 megapixel camera that was the first digital SLR developed entirely by a major manufacturer, and at a cost of under $6,000 at introduction was affordable by professional photographers and high end consumers. This camera also used -mount lenses, which meant film photographers could use many of the same lenses they already owned. Also in 1999, Minolta introduced the RD-3000 D-SLR at 2.7 megapixels. This camera found many professional adherents. Limitations to the system included the need to use Vectis lenses which were designed for APS size film. The camera was sold with 5 lenses at various focal lengths and ranges (zoom). Minolta did not produce another D-SLR until September 2004 when they introduced the Alpha 7D (Alpha in Japan, MaxxumMaxxum in North America, DynDynaxax in the rest of the world) but using the Minolta A-mount system from its 35 mm line of cameras. 2003 saw the introduction of the Canon EOS 300D, also known as the Digital Rebel, a 6 megapixel camera and the first DSLR priced under $1,000, and marketed to consumers.

Sensors and storage Sensors read the intensity of light as filtered through different filters, and digital memory devices store the information, either as RGB or as raw data. There are two main types of sensors: charge-coupled device (CCD) – photocharge is shifted to a central charge-to-voltage converter CMOS sensors ("Active pixel sensor")

Nearly all digital cameras now use built in and/or removable solid state memory. Digital camcordercamcorderss that double as a digital still camera use flash memory,memory, discs and internal hard disks. For a time floppy disks and mini-CDs were used in early digital cameras such as the Sony Mavica range. MultifunctionaMultifunctionalitylity and connectivity Except for some linear array type of cameras at the highest-end and simple web cams at the lowest-elowest-end,nd, a digital memory device (usually flash memory;memory; floppy disks and CD-RWsCD-RWs are less common) is usually used for storing images, which may then be transferred to a computer later. Digital cameras can take pictures, and may also record sound and video. Some can be used as webcams, some can use the PictBridge standard to connect to a printer without using a computer, and some can display pictures directly on a television set. Similarly, many camcorders can take stistillll photog photograpraphs,hs, anandd ststoreore ththemem on videot videotapeape or on flflashash memory memorycarcardsds wiwithth the samee sam functionality as Digital Cameras. Performance metrics The quality of a digital image is the sum of various factors, many of which are similar to film cameras. Pixel count (typically listelistedd in megapixels,megapixels, millions of pixels) is only one of the major facfactortors,s, though though it is ththee most most heavil heavilyy marke marketeted.d. PiPixelxel count count metritrics me cs were were create createdd by the marketinmarketingg organizations of digital camera manufacturersmanufacturers becausebecause consumers can use it to easily compare camera capabilities. It is not, however, the major factor in evaluating a digital camera. The processing system inside the camera that turns the raw data into a color-balanced and pleasing is the most critical, which is why some 4+ megapixel cameras perform better than higher-end cameras. Lens quality: resolution, distortion, dispersion (see Lens (optics)) Capture medium: CMOS, CCD, film, etc. Capture format: pixel count, digital file type (RAW, TIFF, JPEG), (, , 5x4, 10x8). Processing: digital and / or chemical processing of 'negative' and 'print'.

Pixel counts The number of pixels n for a given maximum resolution (w horizontal pixels by h vertical pixels) is the product n = w × h. This yields e. g. 1.92 megapixels (1,920,000 pixels) for an image of 1600 × 1200. The majority of compact (not DSLR) digital cameras have a 4:3 aspect ratio, i.e. w/w/hh = 4/4/3.3. Accor Accordindingg to DiDigitgitalal Photo Photogragraphyphy Reviview Re ew,, the 4:3 raratiotio is becaus becausee "c"comomputputer er monitors are 4:3 ratio, old CCD's always had a 4:3 ratio, and thus digital cameras inherited this aspect ratio." The pixel count quoted by manufacturers can be misleading as it may not be the number of full- colour pixels. For cameras using single-chip image sensors the number claimed is the total number of single-colour-sensitive photosensors, whether they have different locations in the plane, as with the Bayer sensor, or in stacks of three co-located photosensors as in the . However, the images will have different numbers of RGB pixels: the Bayer-sensor cameras produce as many RGB pixels as photosensors via demosaicing (interpolation), while the cameras with Foveon sensors produce uninterpolated image files with one-third as many RGB pixels as photosensors. It is difficult to compare the resolutions based on the megapixel ratings of these two types of sensors, and therefore sometimes subject of dispute.

Resolution Resolution provides an indication of the amount of detail that is captured, but, like the other metrics, resolution is just another factor out of many in determining the quality of an image. FuFurthrthermermoreore,, differ differentent metho methodsds of crcreateatiningg an image image make make it impos impossibsiblele to compapare com re ththee resolutioresolutionsns of cameras simply based on the number of pixels producedproduced by the image sensorsensor.. For example, the Sigma SD14 camera uses Foveon technology, which is quite different from most

other digital cameras. It claims to be a 14 megapixelmegapixel camera, but is generally consideredconsidered to have detail-capturing capabilities roughly equivalent to 9 megapixels in terms of Bayer sensors. The relative increase in detail resulting from an increase in resolution is better compared by looking at the number of pixels across (or down) the picture, rather than the total number of pixels in the picture area. For example, a sensor of 2560 × 1600 sensor elements is described as "4 megapixels" (2560 × 1600 = 4,096,000). IncreasiIncreasinngg to 3200 × 2048 increases the pixels in the picture to 6,553,600 (6.5 megapixmegapixels),els), a factor of 1.6, but the pixels per cm in the picture (at the same image size) increases by only 1.25 times. A measure of the comparative increase in linear resolution is the square root of the increase in area resolution, i.e., megapixels in the entire image. Resolution in pixels is not the only measure of image quality; a larger sensor with the same number of pixels will generally produce a better image than a smaller one. One of the most important difdifferencesferences is an improvementimprovement in . This is one of the advantages of digital SLR cameras, which have larger sensors than simpler cameras of the same resolution.

Dynamic range Practical imaging systems, digital and film, have a limited "dynamic range": the range of luminosity which can be reproduced accurately. Highlights of the subject which are too bright will be rendered as white, with no detail; shadows which are too dark will be rendered as black. The loss of detail is not abrupt with film, or in darkdark shadows with digital sensorssensors:: some detail is retained as brightness moves out of the dynamic range. "Highlight burn-out" of digital sensors, however, can be abrupt, and highlight detail may be lost. And as the sensor elements for different saturate in turn, there can be gross hue or saturation shift in burnt-out highlights. Some digital cameras can show these blown highlights in the image review, allowing the photographer to re-shoot the picture with a modified . Others compensate for the total contrast of a scene by selectively exposing darker pixels longer. A third technique is used by Fujifilm in its FinePix S3 Pro digital SLR. The imageimage sensor contains additionaladditional photodiodes of lower sensitivity than the main ones; these retain detail in parts of the image too bright for the main sensor. High dynamic range imaging (HDR) addresses this issue by increasing the dynamic range of images by either increasing the dynamic range of the image sensor or by using exposure bracketing and post-processing the separate images to create a single image with a higher dynamic range. HDR images curtail burn-outs and black-outs.

With the acceptable image Applicationsquality and the other and adv considerationsantages of (particularly the time pressures of vital importance to daily newspapers) the majority of professional news photographers have begun capturing their images with digital cameras. Digital photography has also been adopted by many amateur snapshot photographers, who take advantage of the convenience of the form when sending images by email, placing them on the World Wide Web, or displaying them in digital picture frames. Digital cameras have also been integrated into many cell phones, although, because of the small, poor quality lenses and sensors in most of these phones, the quality of these pictures makes them unsuitable for making even moderate size prints. Some commercial photographers, and some amateurs interested in artistic photography, have been resistant to using digital rather than film cameras because they believe that the image quality available from a digital camera is still inferior to that available from a film camera, and the quality of images taken on film is near-impossible to match at any price with a digital camera. Some have expressed a concern thatthat changing computer technologytechnology may make digital photographs inaccessible in the future. A related concern in a specialized application is the use of digital photographs in court proceedings, with the added difficulty of demonstrating an

image's authenticity. Some high-end film can also still be projected for viewing at a much higher optical resolution than even the best digital projectors. Other commercial photographers, and many amateurs, have enthusiastically embraced digital photography because they believe that its flexibility and lower long-term costs outweigh its initial price disadvantagesdisadvantages.. Almost all of the cost of digital photography is capital cost, meaningmeaning that the cost is for the equipment needed to store and copy the images, and once purchased requires virtually no further expense outlay. Film photography requires continuous expenditure of funds for supplies and developing, although the equipment itself does not outdate so quickly and has a longer service life. Some commercial photographers have also begun moving to digital techtechnolonologygy because because of the tremendo tremendousus editing editing capabili capabilitiesties now offeredoffered on computer computers.s. The phphotootogragraphepherr is abablele to coloror-ba col -balanlancece and manip manipulaulatete the image image in ways ways that that tradit traditioionalnal techniques cannot offer, although film users can utilize the same technology with a . With fully color-balanced systems from the camera to the monitor to the printer, the photographer can now print what is actually seen on the screen. HoweverHowever,, digital cameras require batteries that need to be rechargedrecharged or replaced frequently,frequently, and this means that a photographerphotographer needs access to electrical outlets.outlets. Digital cameras also tend to be much more sensitive to moisture and extreme cold. For this reason, photographers who work in remote areas may favour film SLR cameras, though manymany higher-endhigher-end DSLRs are now equipped with weather-resistant bodies. Medium- and large-format film cameras are also still preferred by publications insisting on the very highest detail and resolution. Digital photography was used in astronomy long before its use by the general public and had almost completely displaced photographic plates by the early 1980s. Not only are CCDs more

CCDssensitive used to lightin astronomy than plates, are but similar they have to those a muc usedh more by uniformthe general and public,predictable but response.are generally The monochrome and cooled with liquid nitrogen so as to reduce the noise caused by heat. Many astronomical instruments have arrays of many CCDs, sometimes totaling almost a billion pixels. NoNowadwadaysays amateur amateur astrono astronomermerss also commonlycommonly use digital digital cameras, cameras, includingincluding the use of webcams for speckle imaging or "video astronomy".

Sensor size and angle of view Cameras with digital sensors that are smaller than the typical 35mm film size will have a smaller field or angle of view when used with a lens of the same . This is because angle of view is a function of both focal length and the sensor or film size used. If a sensor smaller than the full-frame 35mm film format is used, such as the use of APS-C-sized digital sensors in DSLRs, then the field of view is cropped by the sensor to smaller than the 35mm full-frame format's field of view. This narrowing of the field of view is often described in terms of a focal length multiplier or crop factor, a factor by which a longer focal length lens would be needed to get the same field of view on a full-frame camera. If the digital sensor has approximately the same reresolutionsolution (eff(effectiveective pixelspixels per unit area) as the 35mm film surface (24 x 36 mm), then the result is similar to taking the image from the film camera and cutting it down (cropping) to the size of the sensor. For an APS-C size sensor, this would be a reduction to approximately the center 50% of the image. The cheaper, non-SLR models of digital cameras typically use much smaller sensor sizes and the reduction would be greater. If the digital sensor has a higher or lower density of pixels per unit area thanthan the film equivalent, then the amount of information captured will differ correspondingly. While resolution can be estimated in pixels per unit area, the comparison is complex since most types of digital sensor record only a single colour at each pixel location, and different types of film will have different effeffectiectiveve resoluti resolutions.ons. There are various various trade-of trade-offsfs involved involved,, since since larger larger sensors sensors are moree mor expensive to manufacture and require largerlarger lenses, while sensors with higher numbers of pixels per unit area are likely to suffer higher noise levels.

For these reasons, it is possible to obtain cheap digital cameras with sensor sizes much smaller than 35mm film, but with high pixel counts, that can still produce high-resolutionhigh-resolution images. Such cameras are usually supplied with lenses that would be classed as extremely wide angle on a 35mm camera, and which can also be smaller size and less expensive, since there is a smaller sensor to illuminate. For example, a camera with a 1/1.8" sensor has a 5.0x field of view crop, and so a hypothetical 5-50mm will produce images that look similar (again the differences mentioned above are important) to those produced by a 35mm film camera with a 25–250mm lens, whilwhilee being much more compact than suchsuch a lens for a 35mm35mm camera since the imaging circle is much smaller. This can be useful if extra telephoto reach is desired, as a certain lens on an APS sensor will produce an equivalent image to a significantly longer lens on a 35mm film camera shot at the same distance from the subject, the equivalent length of which depends on the camera's field of view crop. This is sometimes referred to as the focal length multiplier, but the focal length is a physica physicall attribute of the lens and not the camera system itself.itself. The downside to this is that wide angle photography is made somewhat more difficult, as the smaller sensor effectively and undesirably reduces the captured field of view. Some methods of compensating for this or othotherwerwisisee prproduoducicingng much much wiwiderder digitaital dig l phototogra pho graphsphs ininvolvolveve using using a fifishesheyeye lens lens and "defishing" the image in post processing to simulate a rectilinear wide angle lens. Full-fraFull-frameme digital SLRs, that is, those with sensor size matchingmatching a frame of 35mm film, include Canon 1DS, 1DS II, and 5D, Kodak Pro DCS-14n, and N Digital. There are very few digital cameras with sensors that can approach the resolution of larger-format film cameras, with the possible exception of the MamiyaMamiya ZD (22MP) and the HasselbladHasselblad H3D series of DSLRs (22

Commonto 39 MP). values for field of view crop in DSLRs includeinclude 1.3x for some Canon sensors, 1.5x for Sony APS-C sensors used by Nikon, and Konica Minolta and for Fujifilm sensors, 1.6 (APS-C) for most Canon sensors, ~1.7x for Sigma's Foveon sensors and 2x for Kodak and Panasonic 4/3" sensors currently used by Olympus and Panasonic. Crop factors for non-SLR consumer compact and bridge cameras are larger, frequently 4x or more. Drawing showing the relative sizes of sensors used in most current digital cameras.Table of sensor sizes TTyyppee WWiiddtthh ((mmmm)) HHeeiigghhtt ((mmmm))Siizze S e ((mmmm²²)) 11//33..66"" 44..0000 33..0000 1122..00 11//33..22"" 44..5544 33..4422 1155..55 11//33"" 44..8800 33..6600 1177..33 11//22..77"" 55..3377 44..0044 2211..77 11//22..55"" 55..7766 44..2299 2244..77 11//22"" 66..4400 44..8800 3300..77 11//11..88"" 77..1188 55..3322 3388..22 11//11..77"" 77..6600 55..7700 4433..33 22//33"" 88..8800 66..6600 5588..11 11"" 1122..88 99..66 112233 44//33"" 1188..00 1133..55 224433 AAPPSS--CC 2255..11 1166..77 441199 3355mmmm 3366 2244 886644 BBaacckk 4488 3366 11772288

Storage

tapeStorage (Steven for digital Sasson's cameras 1975 prototype)have increased to floppy in size dis andks to technology flash memory. with the time. FromFrom magnetic

Digital camera backs Most digital cameras are built to operate as a self-contained unit. This is especially so at the lower-end, for these cameras usually include zoom lens and flashes that cannot be changed. However, at the highest-end, some digital cameras are nothing but a sophisticated light-sensing unitunit.. Experie Experiencednced photogra photographerpherss attach attach these these digital digital "camera "camera backs" backs" to their their professi professionalonal medium format SLR cameras, such as a . Area array CCD

LinearCMOS array CCD (monochrome) 3-strip CCD with color filters Linear array cameras are also called scan backs. Single-shot Multi-shot (three-shot, usually) Scanning and multi-shot camera backs are usually used only in studios to take pictures of still objects. Most earlier digital camera backs used linear array sensors which could take seconds or even minutes for a complete high-resolution scan. The linear array sensor acts like its counterpart in a flatbed by moving vertically to digitize the image.

Many early such cameras could only capture images. To take a color picture, it required three separate scans done with a rotating colored filter. These are called multi-shot backs. Some other camera backs use CCD arrays similar to typical cameras. These are called single-shot backs. Since it is much easier to manufacture a high-quality linear CCD array with only thousands of pixels than a CCD matrix with millions, very high resolution linear CCD camera backs were available much earlier than their CCD matrix counterparts. For example, you could buy an (albeit expensive) camera back with over 7,000 pixel horizontal resolution in the mid-1990s. However, as of 2004, it is still difficult to buy a comparable CCD matrix camera of the same resolution. Rotating line cameras, with about 10,000 color pixels in its sensor line, are able, as of 2005, to capture about 120,000 lines during one full 360 degree rotation, thereby creating a single digital image of 1,200 Megapixels. Most modern digital camera backs use very large CCD matrices. This eliminates the need for scanning. For example, PhaPhasese One produces a 39 million pixel digital camera bbackack with a 49.1 x 36.8 mm CCD in 2008.2008. This CCD array is a littlelittle smallersmaller than a frame of 120 film and much larger than a 35 mm frame (36 x 24 mm). In comparison, a consumer digital camera usually uses a much smaller 1/2.5 inch or 7.176 x 5.329 mm (~ 1/1.8 inch) CCD sensor.sensor. Further,Further, the 1/2.5 or 1/1.8 inch diagonal measurement is the size of the entire CCD chip- the actual photo-sensitive area is much smaller. At present, there are relatively few complete digital SLR cameras with sensors large enough to compete with medium to film cameras. and Mamiya manufacture medium format digital devices that can capture 16MP up to 39MP[4]. The units tend to be quite large and expensive. Additionally, because of their high build quality and lack of moving parts tend to be quite long lasting and are prominent on the used market [5].

Advantages of consumer digital cameras The advantages of digital photography over traditional film include: Instant review of pictures, with no wait for the film to be developed: if there's a problem with a picture, the photographer can immediately correct the problem and take another picture Minimal ongoing costs for those wishing to capture hundreds of photographs for digital uses, such as computer storage and e-mailing, but not printing.

If one already owns a newer computer, permanent storage on digital media is considerably cheaper than film Photos may be copied from one digital medium to another without any degradation Pictures do not need to be scanned before viewing them on a computer Ability to print photos using a computer and consumer-grade printer Ability to embed metadata within the image file, such as the time and date of the photograph, model of the camera, speed, flash use, and other similar items, to aid in the reviewing and sorting of photographs. Film cameras have limitedlimited ability to handle metadata, though many film cameras can "imprint" a date over a picture by exposing the film to an internal LED array (or other device) which displays the date. Ability to capture and store hundreds of photographs on the same media device within the digital camera; by contrast, a film camera would require regularregular changing of film (typically after every 24 or 36 shots) Many digital cameras now include an AV-out connector (and cable) to allow the reviewing of photographs to an audience using a television Anti-shake functionality (increasingly common in inexpensive cameras) allow taking sharper hand-held pictures where previously a was required Ability to change ISO speed settings more conveniently in the middle of shooting, for example when the weather changes from bright sunlight to cloudy. In film photography, film must be unloaded and new film with desired ISO speed loaded. Smaller sensor format, compared to 35mm film frame, allows for smaller lenses, wider zoom ranges, and greater .

Ability to convertuse the samethe same device photo to capture from color video to assep wellia to as black still images.& white

Advantages of professional digital cameras The Golden Gate Bridge retouched for painterly light effects Immediate image review and deletion is possible; lighting and composition can be assessed immediately, which ultimately conserves storage space. FasFasterter workflow workflow:: Manageme Managementnt (colour (colour and file), file), manipula manipulationtion and printin printingg tools tools are moree mor versatile than conventional film processes. However, batch processing of RAW files can be time consuming, even on a fast computer. Digital manipulation: A digital image can be modified and manipulated much easier and faster than with traditional negative and print methods. The digital image to the right was captured in RAW format, processed and output in 3 different ways from the source RAW file, then merged and further processed for color saturation and other special effects to produce a more dramatic result than was originally captured with the RAW image. Recent manufacturers such as Nikon and Canon have promoted the adoption of digital single- lens reflex cameras (DSLRs) by photojournalists. Images captured at 2+ megapixelsmegapixels are deemed to be of sufficient quality for small images in newspaper or magazine reproduction. Six to 14 megapixel images, found in modern digital SLRs, when combined with high-end lenses, can approximate the detail of film prints taken with 35 mm film based SLRs, and the latest 16 megapixel models can produce astoundingly detailed images which are believed to be better than 35mm film images and the majority of medium format cameras.[6]

Disadvantages of digital cameras Whereas film cameras can have manual backups for electronic and electrical features, digital cameras are entirely dependent on a electrical supply (usually batteries but sometimes power cord when in 'tethered' mode). Many digital sensors have less dynamic range than . However, some newer CCDs such as Fuji's Super CCD, which combines diodes of different sensitivity, have improved this issue.

When highlights burn out, they burn to white without details, while film cameras retain a reduced level of detail, as discussed above. High ISO image noise manifests as multicoloredmulticolored speckles in digital images, rather thanthan the less-less- objectionaobjectionableble "grain" of high-ISO film. While this speckling can be removed by noise-reduction softwarsoftware,e, either in-camera or on a computer,computer, this can have a detrimentaldetrimental effect on image quality as fine detail may be lost in the process. Aliasing may add patterns to images which do not exist and would not appear in film. For most consumers in prosperous countries such as the United States and Western Europe, the advaadvantagntageses of digital digital cameras cameras outweigh outweigh their their disadvan disadvantagetages.s. However However,, many professi professionalonal photographers continue to prefer film. Much of the post-shooting work done by a photo lab for film is done by the photographer himself for digital images. Concerns that have been raised by professional photographers include: editing and post-processing of RAW files can take longer than 35mm film, downloading a large number of images to a computer can be time-consuming, shooting in remote sites requires the photographer to carry a number of batteries and add to the load to carry, equipment failure—while all cameras may fail, some film camera problems (e.g., meter or rangefinder problems, failure of only some shutter speeds) can be worked around. As time passes, it is expected that more professional photographers will switch to digital. In some cases where very high-resolution digital images of good quality are needed it may be advantageous to take large-format film photographs and digitise them. This allows the creation of very large computer files without speed or capacity disadvantages at picture-taking time.[7]

Equivalent features Noise in a digital camera's image is remarkably similar to film grain in a film camera. At high ISO levels () the grain/noisegrain/noise becomes more apparent in the final image. AlthoughAlthough film ISO levels can be lower than digital ISO levels (25 and 50 respectively), digital settings can be changed quickly according to requirements, while film must be physically replaced and protected from all light during such replacement. Additionally, image noise reduction techniques can be used to remove noise from digital images and film ggrainrain is fixed. From anan artistic point of view,,view film grain and image noise may be desirable when creating a specific mood for an image. Modern digital cameras have comparable noise/grain at the same ISO as film cameras. Some digital cameras though, do exhibit a pattern in the digital noise which is not found on film. Speed of use Previously digital cameras had a longer start-up delay compared to film cameras, i.e., the delay from when they are turned on until they are ready to take the first shot, but this is no longer the case for modern digital cameras. Similarly, the amount of time needed to write the data for a digital picture to the memory card is now comparablecomparable to the amount of time it takes to wind the film on a film camera, at least with modern digital cameras and modern fast memory cards. Both digital cameras and film cameras have a small delay between when the shutter button is pressed and when the picture is taken – this is the time necessarynecessary to the lens andand compute and set the exposure. (This shutter delay is practically zero for SLR and DSLR cameras.)

Frame rate The Canon EOS-1D Mark III can take still photographs at 10 frames per second; the fastest film SLR could shoot 10 frames per second. The Nikon F5 is limited to 36 continuous frames (the length of the film) while the Canon EOS-1D Mark III is able to take about 110 high definition JPEG images before its buffer must be cleared and the remaining space on the storage media can be used. Image longevity

digitalAlthough images digital are imagestored datacan decaydoes notor become degrade corrupt,corru (filmpt, stock leading can to fade), a loss the of imagemedia integrity.integrityon which. Film the should be stored under archival conditions for maximum longevity; this should not be a problem

for digital images as perfect copies can be made and stored elsewhere. Without backup it is easier to lose huge amounts of digital data, for example by accidental deletion of folders, or by failure of a mass storage device. In comparison, eacheach generatigenerationon of copies of film negatives and transparetransparenciesncies is degraded compared to its parent. Film imagesimages can easily be converted to digitaldigital with some possible loss of quality. Colour reproduction Colour reproductireproductionon (gamut) is dependent on the type and quality of film or sensor used and the quality of the optical system and film processing. Different films and sensors have different color

mediasensitivity; used theto ensurephotographer accurate needs colour to reproduction.understand his Many equipment, digital thecameras light conditions,offer RAW andformat the (sensor data) which makes it possible to choose color space in the developmentdevelopment stage regardless of camera settings; in effect the scene itself is stored as far as the sensor allows, and can to some extent be "rephotographed" with different , exposure, etc.

A comparison of frame aspect ratios A typical digital camera's aspect ratio is 1.33 (4:3), the same as today's NTSC or PAL/SECAM TVs or earliest movies. However, a 35 mm picture's aspect ratio is 1.5 (3:2). Several new digital cameras will take photos in either ratio and nearly all digital SLRSLRss take pictures in a 3:2 ratio as they usually use lenses designed for 35 mm film (Olympus and Panasonic digital SLRs are notable exceptionexceptions).s). Some photo labs also offer the option of printingprinting photos on 4:3 ratio paper,,paper as well as the existing 3:2. In 2005 Panasonic launched the first consumer camera with a native

sizeaspect for ratio APS of film. 16:9, Different matching aspect HDTV. ratios This are is onesimila ofr theto amain 7:4 aspectreasons ratio, consumers which was have a croppingcommon issues when printing digital photos, or film photos as well. Moreover, the majority of digital cameras take an aspect ratio of 4:3 which translates to a size of 4.5" x 6.0". This translates into losing a half an inch when printing on the "standard" size of 4" x 6", an aspect ratio of 3:2. Similar cropping occurs when printing on other sizes as well, i.e., 5"x7", 8"x10", or 11"x14". The easy way to see if the aspect ratio you want will fit is to divide the length and width. If these match then there will be no cropping off the original image. For example, an 8"x12" has the same aspect ratio as a 4"x6" or a 12"x18", because 12 divided by 8 is 1.5, the same aspect ratio as a 4"x6", which is also 1.5. Market impact In late 2002, 2 megapixel cameras were available in the United States for less than $100, with some 1 megapixel cameras for under $60. At the same time, many discount stores with photo labs introduced a "digital front end", allowing consumers to obtain true chemical prints (as opposed to ink-jet prints) in an hour. These prices were similar to those of prints made from film negatives. However, because digital images have a different aspect ratio than 35 mm film images, people have started to realize that 4x6 inch prints crop some of the image off the print. Some photofinishers have started offering prints with the same aspect ratio as the digital cameras record. In July 2003, digital cameras entered the single-use market with the release of the Ritz Dakota Digital, a 1.2 megapixel (1280 x 960) CMOS-based digital camera costing only $11 (USD). FollowiFollowingng the familiarfamiliar single-use concept long in use with film cameras, the Dakota Digital was intended to be used by a consumer one time only.only. When the pre-programmedpre-programmed 25 picture limit is reached, the camera is returned to the store, and the consumer receives back prints and a CD- ROM with their photos. The camera is then refurbished and resold. Since the introduction of the Dakota Digital, a number of similar single-use digital cameras have appeared. Most of the various single-use digital cameras are nearly identical to the original Dakota Digital regarding specspecifiificaticationsons and function functionalitalityy,, although although a few include include superio superiorr specific specificatioationsns and more advanced functions (such as higher image resolutions and LCD screens). Most, if not all, of these single-use digital cameras cost less than $20 (USD), not including processing fees. However, the

huhugege dedemamandnd foforr cocompmplelexx didigigitatall cacamemerarass at cocompmpetetititivivee prpriciceses hahass ofoftetenn reresusultlteded inin manufacturing shortcuts, evidenced by a large increase in customer complaints over camera malfunctmalfunctions,ions, high parts prices, and short service life. SomeSome digital cameras offer only a 90-day warranty. The price of 35mm compact cameras have dropped with manufacturers further outsourcing to countries such as China. Kodak announced in January 2004 that they would no longer sell Kodak-braKodak-brandednded film cameras in the developed world. In JanuaryJanuary 2006, Nikon followedfollowed suit and announced that they will stop the production of all but two models of their film cameras, they will continue to produce the low-end Nikon FM10, and the high-end Nikon F6. In the same month, Konica Minolta announced that it was pulling out of the camera business altogether.altogether. The price of 35mm and APS compact cameras have dropped, probably due to direct competition from digital and the resulting growth of the offer of second-hand film cameras. Pentax have reduced producti productionon of film cameras but not halted it. The technology has improvimproveded so rapidly that one of Kodak's film cameras was discontinued before it was awarded a "camera of the year" award later in the year. Since 2002, digital cameras have outsold film cameras. However, the use of 35mm cameras is greater in developing countries. In Guatemala, for example, extremextremelyely high import duties on all digital products serves to encourage sales and use of film cameras. The decline in film camera sales has also led to a decline in purchases of film for such cameras. In November 2004, a German division of Agfa-Gevaert, AgfaPhoto, split off. Within six months it filed for bankruptcy . Konica Minolta Photo Imaging, Inc. will end production of Color film and paper worldwide by March 31, 2007. In addition, by 2005, Kodak employed less than a third

industryof the employees have been that offset it had in the twenty digital years image earlier. industry. It is not known if these job losses in the film In addition, digital photography has resulted in some positive market impacts as well. The increasinincreasingg popularity of products such as digital photo framesframes and canvas prints is a direct result of the increasing popularity of digital photography. An example of digital photography. This photo was taken and made into a digital print in less than 5 minutes. Social impact Throughout the , technological advances in optics, camera production, developingdeveloping,, and imaging have had an effect on the way people view images. Prior to the 1970s, most people in the United States used slide (or "chrome") film and viewed the images with a . After that, people began to make prints from color negatives. The simultaneous increased use of the Internet and email, relatively cheap computers and digital cameras led to a

Intremendous the early increasepart of the in the21st number century, of thephotographic dominant imethodmages inof digital viewing formats. still images has been on computers and, to a lesser extent, on cellular phones (although people still make and look at prints). These factors have led to a decrease in film and film camera sales and film processing, and has had a dramatic effect on companies such as Fuji, Kodak, and Agfa. In addition, many stores that used to offer photofinishphotofinishinging services oror sell film no longer do, and those thatthat do have seen a tremendous decline. Photographic images have always been prone to fading and loss of image quality due to sun exposure or improper storage of film negatives, slides, and prints. Since digital images are stored as data on a computer, the image never loses visual quality, detail, or fidelity as long as the digital media upon which it is stored remains intact. The only way to ruin a digital image is to delete the image file, to corrupt or re-write some of the image file's data, or to damage or destroy the electronic storage media (hard drive, disk, CD-ROM, flash card, etc.) upon which the file resides. As with all computer files, making backups is the most effectiveeffective way of ensuring that a copy of a digital image can always be recovered. Of growiwing gro ng coconcencernrn for both both ararchichivisviststs and histor historianianss is ththee relatiative rel ve non-pe non-permrmaneanencence or transitory nature of digital media. Unlike film and print, which are tangible and immediately

accessible to a person, storage of digital images is ever-changing with old media and decoding softwarsoftwaree becoming obsoleted or inaccessibleinaccessible by new technologies. HistoriansHistorians are concerned that we are creating a historical void where information and details about a given decade or era will have been lost within either failed or inaccessible digital media. It is recommended that both professional and amateur users develop strategies for migrating stored digital images from old technologies to new. Scrapbookers who may have used film for creating artistic and personal memoirs may need to modify their approach to digital photobooks in order to personalise them and retain the special qualities of traditional photo albums. It is likely that film will never again be purchased and used on the scale it was for most of the 20th century. However, it probably will not disappear altogether. At its advent in the early 19th centurycentury,, many believed photography wouldwould supplant the painting of portraits and landscapes.landscapes. In the same way that acrylic and oil paint are still dominant media in use by artists and hobbyists, it is likely that photographic film and equipment will continue to be an option for enthusiasts.enthusiasts. It is also important to note that the differences between film and digital photography are far less significant than the differences between painting and film photography.

Recent research and innovation Research and development continues to refine the lighting, optics, sensors, processing, storage, display, and software used in digital photography. Here are a few examples. 3D models can be created from collectionscollections of normal images. The resultingresulting scene can be viewed from novel viewpoints, but creating the model is very computationallycomputationally intensive. AnAn example is Microsoft's Photosynth, which provides some models of famous places as examples. High dynamic range cameras and displaysdisplays are commerciallycommercially available. >120 decibel sensors are in development, and software is also available to combinecombine multiplmultiplee non-HDR images (shot with different exposures) into an HDR image. Motion blur can be dramatically removed by a flutter shutter (a flickering shutter which adds a signature to the blur, which postprocessing can recognize). It is not yet commercially available. An object's specular reflection can be captured using computer controlled lights and sensors. This is needed to create attractive images of oil paintings, for instance. It is not yet commercially available, but is starting to be used by museums. Dust reduction systems are being put into cameras to help keep dust off of image sensors in digital SLRs. In a recent study, it was discovered that prolonged exposure to flash photography, particularly by professional equipment, could deteriorate the cornea to such a state that infection could occur and risk of eye cancer could become a far greater risk. The results of this study were presented to

recognisedthe Department by the ofgeneral Health, public. to which they replied the study was flawed and should not be Other areas of progress include improved sensors, more powerful software, enlarged-gamut displays, and computer controlled lighting.

Used abbreviations: