Digital photography is the art and science of producing and manipulating digital photographs — photographs that are represented as bit maps. Digital photographs can be produced in a number of ways:
- Directly with a digital camera
- By capturing a frame from a video
- By scanning a conventional photograph
Once a photograph is in digital format, you can apply a wide variety of special effects to it with image enhancing software. You can then print the photo out on a normal printer or send it to a developing studio which will print it out on photographic paper.
Although the resolution of digital photos is not nearly as high as photos produced from film, digital photography is ideal when you need instant, low-resolution pictures. It's especially useful for photos that will be displayed on theWorld Wide Web because Web graphics need to be low resolution anyway so that they can be downloadedquickly.
Practical imaging systems both 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.
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
Turn of the century digital cameras had a long 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 seconds. 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, 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.)
While some film cameras could reach up to 10 fps, like the Canon EOS-1V HS, professional digital SLR cameras can take still photographs at highest frame rates. While the Sony SLT technology allows rates of up to 12 fps, the Canon EOS-1Dx can take stills at a 14fps rate. 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 10 frame/s and Panasonic Lumix DMC-FZ100 has 11 frame/s. Moreover FinePix HS10 can take movies at 1000 frame/s at 224x64 pixels with no sound
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 (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 is stored as far as the sensor allows, and can to some extent be "rephotographed" with different color balance, exposure, etc.