Digital photography

Nikon D700 — a 12.1 megapixel full-frame DSLR

The Canon EOS 350D

The Canon PowerShot A95

Digital photography is a form of photography that uses an array of light sensitive sensors to capture the image focused by the lens, as opposed to an exposure on light sensitive film. The captured image is then stored as a digital file ready for digital processing (colour correction, sizing, cropping, etc.), viewing or printing.

Until the advent of such technology, photographs were made by exposing light sensitive photographic film and used chemical photographic processing to develop and stabilize the image. By contrast, digital photographs can be displayed, printed, stored, manipulated, transmitted, and archived using digital and computer techniques, without chemical processing.

Digital photography is one of several forms of digital imaging. Digital images are also created by non-photographic equipment such as computer tomography scanners and radio telescopes. Digital images can also be made by scanning conventional photographic images.

History

Main article: History of the camera § Digital Cameras

Sensors and storage

Image sensors read the intensity of light, and digital memory devices store the digital image information 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 use built-in and/or removable solid state flash memory. Digital tapeless camcorders that double as a digital still camera use flash memory, discs and internal hard drives. Certain 20th century digital cameras such as the Sony Mavica range used floppy disks and mini-CDs.

Multifunctionality and connectivity

Except for some linear array type of cameras at the highest-end and simple web cams at the lowest-end, a digital memory device (usually a memory card; floppy disks and CD-RWs are less common) is used for storing images, which may 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 still photographs, and store them on videotape or on flash memorycards with the same functionality as digital cameras.

Performance metrics

The quality of a digital image is a composite of various factors, many of which are similar to those of film cameras. Pixel count (typically listed in megapixels, millions of pixels) is only one of the major factors, though it is the most heavily marketed figure of merit. Digital camera manufacturers advertise this figure because consumers can use it to easily compare camera capabilities. It is not, however, the major factor in evaluating a digital camera for most applications. The processing system inside the camera that turns the raw data into a color-balanced and pleasing photograph is usually more critical, which is why some 4+ megapixel cameras perform better than higher-end cameras.

Resolution in pixels is not the only measure of image quality. A larger sensor with the same number of pixels generally produces a better image than a smaller one. One of the most important differences is an improvement in image noise. This is one of the advantages of digital SLR cameras, which have larger sensors than simpler cameras of the same resolution.

• Lens quality: resolution, distortion, dispersion (see Lens (optics))
• Capture medium: CMOS, CCD, negative film, reversal film etc.
• Capture format: pixel count, digital file type (RAW, TIFF, JPEG), film format (135 film, 120 film, 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 as well as some DSLR digital cameras have a 4:3 aspect ratio, i.e. w/h = 4/3. According to Digital Photography Review, the 4:3 ratio is because "computer 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 Foveon X3 sensor. However, the images have different numbers of RGB pixels: Bayer-sensor cameras produce as many RGB pixels as photosensors via demosaicing (interpolation), while 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.

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). Increasing to 3200 × 2048 increases the pixels in the picture to 6,553,600 (6.5 megapixels), 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.

Dynamic range

Practical imaging systems, digital and film, have a limited "dynamic range": the range of luminosity that can be reproduced accurately. Highlights of the subject that are too bright are rendered as white, with no detail; shadows that are too dark are rendered as black. The loss of detail is not abrupt with film, or in dark shadows with digital sensors: 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 colors 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 exposure. 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 image sensor contains additional 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 problem 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.

Further information: [[:Exposure]]

Applications and considerations

The Presidential Portrait of Barack Obama was the first official U.S. Presidential Portrait to be taken with a digital camera.

With the acceptable image quality and the other advantages of digital photography (particularly the time pressures of daily newspapers) the majority of professional news photographers capture their images with digital cameras.

Digital photography has also been adopted by many amateur snapshot photographers, who take advantage of the convenience of sending images by email, placing them on the World Wide Web, or displaying them in digital picture frames. The majority of cameras are camera phones integrated into cell phones but their usual small, poor quality lenses and sensors render most of 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 medium format film was thought to be impossible to match with a digital camera. Some have expressed a concern that changing computer technology 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. Some professional photographers resist the use of Digital Cameras because they are poor performers when it comes to speed for multiple shots. Storing an 8MP image takes a lot of time and therefore some applications Digital Cameras are not currently appropriate.

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 disadvantages. Almost all of the cost of digital photography is capital cost, meaning 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 technology because of the tremendous editing capabilities now offered on computers. The photographer is able to color-balance and otherwise manipulate the image in ways that traditional darkroom techniques cannot offer, or are far more laborious in the darkroom. With fully color-balanced systems from the camera to the monitor to the printer, the photographer can now supply, either as a print or as a computer display, what is actually seen on the photographer's screen. Film users can use a film scanner, thus mixing the two technologies. Rapid advances in the technologies have resulted in many specialised abbreviations and initialisms being freely used in publications and internet discussions.

However, digital cameras require batteries that need to be recharged or replaced frequently, and this means that a photographer needs access to electrical 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 many higher-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 astrophotography long before its use by the general public and had almost completely displaced photographic plates by the early 1980s. CCDs are more sensitive to light than plates, and have a much more uniform and predictable response. The CCDs used in astronomy are similar to those used by the general public, but are generally monochrome. Many of those used in infrared astronomy are cooled with liquid nitrogen so as to reduce the image noise caused by heat. Many astronomical instruments have arrays of many CCDs, sometimes totaling almost a billion pixels. Amateur astronomers also commonly use digital cameras, including the use of webcams for speckle imaging or "video astronomy".

Sensor size and angle of view

Cameras with digital image sensors that are smaller than the typical 35mm film size has a smaller field or angle of view when used with a lens of the same focal length. 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 resolution (effective pixels 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 the center 62.5% 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 than the film equivalent, then the amount of information captured differs 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 have different effective resolutions. There are various trade-offs involved, since larger sensors are more expensive to manufacture and require larger 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-resolution images. Such cameras are usually supplied with lenses that would be classed as extremely wide angle on a 35mm camera, and that 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 zoom lens produces images that look similar (again the differences mentioned above are important) to those produced by a 35mm film camera with a 25–250mm lens, while being much more compact than such a lens for a 35mm 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 produces an image equivalent 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 physical attribute of the lens and not the camera system itself. The disadvantage of 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 otherwise producing much wider digital photographs involve using a fisheye lens and "defishing" the image in post processing to simulate a rectilinear wide angle lens.

Full-frame digital SLRs, that is, those with sensor size matching a frame of 35mm film, include Canon 1Ds and 5D series, Kodak Pro DCS-14n, Nikon D3 line and Contax 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 Mamiya ZD (22MP) and the Hasselblad H3D series of DSLRs (22 to 39 MP).

Common values for field of view crop in DSLRs include 1.3x for some Canon (APS-H) sensors, 1.5x for Sony APS-C sensors used by Nikon, Pentax 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.

Further information: [[:Image sensor format]]

Relative sizes of sensors used in most current digital cameras.

Table of sensor sizes
Type	Width (mm)	Height (mm)	Size (mm²)
1/3.6"	4.00	3.00	12.0
1/3.2"	4.54	3.42	15.5
1/3"	4.80	3.60	17.3
1/2.7"	5.37	4.04	21.7
1/2.5"	5.76	4.29	24.7
1/2"	6.40	4.80	30.7
1/1.8"	7.18	5.32	38.2
1/1.7"	7.60	5.70	43.3
2/3"	8.80	6.60	58.1
1"	12.8	9.6	123
4/3"	18.0	13.5	243
APS-C	25.1	16.7	419
35 mm	36	24	864
Back	48	36	1728

Storage

Main article: Digital camera § Storage

Storage for digital cameras has increased in size and technology with time, from magnetic tape (Steven Sasson's 1975 prototype) to floppy disks to flash memory.

Digital camera backs

Main article: digital camera back

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 unit. Experienced photographers attach these digital "camera backs" to their professional medium format SLR cameras, such as a Mamiya.

• Area array
  • CCD
  • CMOS
• Linear 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 that could take seconds or even minutes for a complete high-resolution scan. The linear array sensor acts like its counterpart in a flatbed image scanner by moving vertically to digitize the image.

Many early such cameras could only capture grayscale 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, Phase One produces a 39 million pixel digital camera back with a 49.1 x 36.8 mm CCD in 2008. This CCD array is a little smaller 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. 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 large format film cameras. Phase One and Mamiya manufacture medium format digital devices that can capture 16MP up to 39MP. 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.

Comparison with film photography

Main article: Digital versus film photography

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, shutter speed, flash use, and other similar items, to aid in the reviewing and sorting of photographs. Film cameras have limited 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) that 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 regular 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 tripod 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 depth of field.
• Ability to use the same device to capture video as well as still images.
• Ability to convert the same photo from color to sepia to black & 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.
• Faster workflow: Management (colour and file), manipulation and printing tools are more 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+ megapixels are deemed of sufficient quality for small images in newspaper or magazine reproduction. Eight to 24 megapixel images, found in modern digital SLRs, when combined with high-end lenses, can approximate the detail of film prints from 35 mm film based SLRs, and the latest 16 megapixel models can produce detailed images that are thought better than 35mm film images and the majority of medium format cameras.

Disadvantages of digital cameras

• Whereas film cameras can have manual backups for electronic and electrical features, digital cameras are entirely dependent on an electrical supply (usually batteries but sometimes power cord when in 'tethered' mode).
• Many digital sensors have less dynamic range than color print film. However, some newer CCDs such as Fuji's Super CCD, which combines diodes of different sensitivity, have improved upon 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 may manifest as multicolored speckles in digital images, rather than the less-objectionable "grain" of high-ISO film. While this speckling can be removed by noise-reduction software, either in-camera or on a computer, this can have a detrimental effect on image quality as fine detail may be lost in the process.
• Aliasing may add patterns to images that do not exist and would not appear in film.
• The possibility that in the future certain digital file formats (for example, JPEG) may become obsolete/replaced.
• Dust particles can adhere to the cover glass of the image sensor in digital cameras, resulting in persisting dust spots in images. Film cameras use a fresh piece of film for each shot, so dust does not build up on the film. Digital image sensors may be cleaned with a simple cleaning kit or professionally, and some digital cameras have built-in sensor cleaning mechanisms, mitigating this problem.

For most consumers in prosperous countries such as the United States and Western Europe, the advantages of digital cameras outweigh their disadvantages. However, some professional photographers still 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.

Equivalent features

Image noise / grain

Noise in a digital camera's image is remarkably similar to film grain in a film camera. At high ISO levels (film speed) the grain/noise becomes more apparent in the final image. Although 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 grain is fixed. From an artistic point of 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 that 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 with start-up times under 1/4 second (0.15 seconds for the Nikon D90). Similarly, the amount of time needed to write the data for a digital picture to the memory card is now comparable 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 necessary to autofocus the lens and compute and set the exposure. (This shutter delay is practically zero for SLR and the best DSLR cameras.)

Frame rate

The Nikon D3 can take still photographs at 11 frames per second; the fastest film SLR could shoot 14 frames per second (Canon F1-n with a super high speed motor, but fewer than 100 were constructed for the 1984 Summer Olympics). 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. Even Bridge camera such as Fujifilm FinePix HS10 has burst mode 10fps and Panasonic Lumix DMC-FZ100 has 11fps. Moreover FinePix HS10 can take movies at 1000 fps at 224x64 pixels with no sound.

Image longevity

Film and prints can fade, but digital images can potentially last unchanged forever. However, the media on which the digital images are stored can decay or become corrupt, leading to a loss of image integrity. Film and digital media should be stored under archival conditions for maximum longevity. 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, each generation of copies of film negatives and transparencies is degraded compared to its parent. Film images can easily be converted to digital (by using a digital film scanner for example) with some possible loss of quality.

Colour reproduction

Colour reproduction (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 sensitivity; the photographer needs to understand his equipment, the light conditions, and the media used to ensure accurate colour reproduction. Many digital cameras offer RAW format (sensor data), which makes it possible to choose color space in the development 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 color balance, exposure, etc. Although RAW format can be used, the sensor and the cameras dynamics can only capture in the GAMUT that the system will allow, and when that image is transferred for reproduction on any device the best possible gamut that the person viewing the image will see is the gamut of the end device for a monitor it would be the screens gamut, for a photgraphic print it will be the gamut of the device that printed the image on the paper. Color Gamut or Color Space is an abstract term for describing an area where points of color fit in a three dimensional space. You might more easily picture this as different shaped/sized boxes whereby one box may not fit into another and therefore what does not fit gets clipped off.

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 take photos in either ratio, and nearly all digital SLRs take pictures in a 3:2 ratio as they usually use lenses designed for 35 mm film (Olympus and Panasonic digital SLRs are notable exceptions). Some photo labs print photos on 4:3 ratio paper, as well as the existing 3:2. In 2005 Panasonic launched the first consumer camera with a native aspect ratio of 16:9, matching HDTV. This is similar to a 7:4 aspect ratio, which was a common size for APS film. Different aspect ratios is one of the reasons consumers have cropping issues when printing digital photos, or film photos. 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, i.e., 5"x7", 8"x10", or 11"x14". The easy way to see if the aspect ratio you want fits is to divide the length and width. If these match, there is no cropping of 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 disposable camera market with the release of the Ritz Dakota Digital, a 1.2 megapixel (1280 x 960) CMOS-based digital camera costing only $11 (USD). Following the familiar single-use concept long in use with film cameras, the Dakota Digital was intended to be used by a consumer one time only. When the pre-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 specifications and functionality, although a few include superior specifications 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 huge demand for complex digital cameras at competitive prices has often resulted in manufacturing shortcuts, evidenced by a large increase in customer complaints over camera malfunctions, high parts prices, and short service life. Some digital cameras offer only a 90-day warranty.

Prices 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-branded film cameras in the developed world. In January 2006, Nikon followed suit and announced they would stop 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 it was pulling out of the camera business 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 production of film cameras but not halted it. The technology has improved 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, extremely 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. ended production of Color film and paper worldwide by March 31, 2007. In addition, by 2005, Kodak employed less than a third of the employees it had twenty years earlier. It is not known if these job losses in the film industry have been offset in the digital image industry.

In addition, digital photography has resulted in some positive market impacts as well. The increasing popularity of products such as digital photo frames and canvas prints is a direct result of the increasing popularity of digital photography.

File:Tribunebackground02192006.JPG

An example of digital photography. This photo was taken and made into a digital print in less than 5 minutes.

Social impact

Throughout the history of photography, technological advances in optics, camera production, developing, and imaging have had an effect on the way people view images. Up until 1960, most printed photographs were black and white. Cameras that could print colour film began to be popular in the 1960s, particularly with the introduction of the Polaroid camera invented by Edwin Land, which could print out a colour film print directly from the camera, within a few minutes of taking the picture. Up until the advent of the digital camera, amateur photographers could either buy print film for their camera, or slide film. If they purchased slide film, the resulting slides could be viewed using a slide projector. Digital photography began to be available in the early 2000s. The simultaneous increased use of the Internet and email, relatively cheap computers and digital cameras led to a tremendous increase in the number of photographic images in digital formats.

In the early part of the 21st century, the dominant method of viewing 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 photofinishing services or sell film no longer do, and those that 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 remains intact. The only way to ruin a digital image is to delete the image file, corrupt or re-write some of the image file's data, or damage or destroy the electronic storage media (hard drive, disk, CD-ROM, flash card, etc.) that contains the file. As with all computer files, making backups is the most effective way of ensuring a digital image can be recovered.

Of growing concern for both archivists and historians is the relative non-permanence 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 software becoming obsoleted or inaccessible by new technologies. Historians 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 century, many believed photography would supplant the painting of portraits and 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 remain an option for 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.

The web has been a popular medium for storing and sharing photos ever since the first photograph was published on the web by Tim Berners-Lee in 1992 (an image of the CERN house band Les Horribles Cernettes). Today popular sites such as Flickr, Picasa and PhotoBucket are used by millions of people to share their pictures.

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 collections of normal images. The resulting scene can be viewed from novel viewpoints, but creating the model is very computationally intensive. An example is Microsoft's Photosynth, which provides some models of famous places as examples.
• High dynamic range cameras and displays are commercially available. >120 decibel sensors are in development, and software is also available to combine multiple non-HDR images (shot with different exposures) into an HDR image.
• Motion blur can be dramatically removed by a flutter shutter (a flickering shutter that adds a signature to the blur, which postprocessing recognizes). 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 to help keep dust off of image sensors, originally introduced only by a few cameras like Olympus DSLRs, have now become standard in most models and brands.

Other areas of progress include improved sensors, more powerful software, enlarged-gamut displays, and computer controlled lighting.

See also

• Analog photography
• Automatic image annotation
• Camcorder
• Chimping
• Design rule for Camera File system
• Digital camera
• Digital image editing
• Digital imaging
• Digital photo frame
• Digital Print Order format (DPOF)
• Digital revolution
• Digital single-lens reflex camera
• Digital watermarking
• Exif Exchangeable image file format
• Geocoded photo
• High dynamic range imaging
• Lenses for SLR and DSLR cameras
• List of digital camera brands
• Mini-USB 4 pin port
• Online proofing
• Personal storage device (PSD)
• Photo sharing
• PictBridge
• POTD
• Raw image format
• Society for Imaging Science and Technology, IS&T

External links

• Template:Dmoz
• Digital Photography FAQ
• Digital Photography Terminology