Digital Photography
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Moscow state university Faculty of Computational MathematicMathematicss and Cybernetics Digital photography Strjelbitskaja Maria, Moscow, 2009 Contents 1 History 2 Sensors and storage 3 Multifunctionality and connectivity 4 Performance metrics 4.1 Pixel counts 4.2 Resolution 5 Dynamic range 6 Applications and considerations 7 Sensor size and angle of view 8 Storage 9 Digital camera backs 10 Comparison with film photography 10.1 Advantages of consumer digital cameras 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 photographic film to create imimageagess whwhicichh coucouldld be mamadede visvisibliblee by phophotogtograpraphichic proprocescessinsing.g. By concontrtrastast,, digdigitaitall photographs can be displayed, printed, stored, manipulated, transmitted, and archived using digital and computer techniques, without chemical processing. non-non-photDigitalphotogra photographyographicphic equiequipme is onepment ofnt severalsuch asforms compcomputer ofuter digi taltomtomogra imaging.ographyphy Digital scanscannersners images and are radiradio alsoo teletelescopcreatedscopes. 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 planplanetet provprovidedided addiadditiontionalal stadstadiameiametrictric infoinformatrmationion for orbiorbitingting and lanlandingding guidance. The concept included camera design elements foreshadowing the first digital camera. 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 Kodak. It used the then- new solid-state CCD image sensor chips developed by Fairchild Semiconductor in 1973. The camera weighed 8 pounds (3.6 kg), recorded black and white images to a cassette tape, had a resolution of 0.01 megapixels (10,000 pixels), 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 movie camera 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 prototyprototypepe of this model at the 1984 SummeSummerr 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 uutilitytility and the ability to transmit images by telephone lines. The poor image quality was offset by the low resolutioresolutionn of newspapnewspaperer graphics. This capability to transmitransmitt 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 Nikon QV-1000C, designed as a press camera 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 Nikons. 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) cameracamerass builbuiltt for utilutilityity.. In 1997 the firfirstst megmegapixapixelel camecamerasras for consconsumeumersrs werweree 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 Nikon F-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, MaxxuMaxxumm 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 color filters, and digital memory devices store the digital image information, either as RGB color space 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 flash memory. Digital camcordercamcorderss that double as a digital still camera use flash memorymemory,, 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 memorymemory;; floppy disks and CD-RCD-RWsWs 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 phophotogtograpraphs,hs, anandd ststoreore ththemem on vidvideoteotapeape or on flflashash memmemoryorycarcardsds wiwithth the samsamee 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 megapixelmegapixels,s, millions of pixels) is only one of the major facfactortors,s, thothoughugh it is ththee momostst heaheavilvilyy mamarkerketeted.d.