Digital cameras save images in various formats including RAW and JPEG.
Digital cameras save images in various file formats including JPEG, TIFF and RAW. The major camera manufacturers each have a proprietary RAW format used in their digital cameras. Some of the major RAW formats include Nikon's NEF format, Canon's CR2 format and Pentax's PEF format. While each manufacturer has its own special formula for creating RAW files, each type delivers an uncompressed image file.
RAW Defined
All digital cameras record image data as unprocessed, uncompressed information. Manufacturers refer to this unprocessed information as RAW (no acronym, just RAW) because the information consists of only what was recorded by the camera's imaging chip. Once the image data is recorded, digital cameras typically save the image as a RAW file or a JPEG file. While all cameras record uncompressed data, typically point-and-shoot and some bridge cameras (not a point-and-shoot but not quite a DSLR) require the user to save the image as a JPEG file. RAW files contain either 12 bits of data or 14 bits of data. A 12-bit chip allows each pixel to record 4,096 levels of brightness, whereas a 14-bit chip records 16,384 levels of brightness at each pixel.
RAW Mode Selection
The majority of DSLR cameras have the ability to store images as RAW or JPEG files, and some can even store each image as both file types simultaneously. Because RAW files contain uncompressed data, shooting in RAW results in a larger file size than an image captured and stored as a JPEG file. Selecting the RAW mode on a camera depends on the camera's functionality, but most often the option is found in the camera's menu section under "Image Size" or "Image Format."
The Undeveloped Image
A RAW file is comparable to an undeveloped negative. An undeveloped negative contains only the exposure information recorded by the camera during the actual exposure of the film. During the development of the negative the photographer can alter that information by over-developing the negative, under-developing the negative, using certain chemicals to alter the information in the negative and many other darkroom tricks. RAW files allow the same sort of post-capture image manipulation without committing the adjustments to the actual file.
Non-destructive Information
Despite the settings a photographer might use when photographing in RAW, the RAW file only gets tagged with specific information such as white balance, color and contrast information. The information does not reside in the actual image. In other words, if a photographer sets his white balance manually, the RAW image only contains that information tagged in the file's header information, it does not commit her manual adjustment to the actual image. This allows the photographer to manually adjust the white balance during post-processing anyway she likes. On the other hand JPEG files write information to the image itself, making any post-processing adjustments difficult and not as accurate. Additionally, RAW files require specific software to convert the RAW file into a format that a computer can open and read. Having total control to manipulate the image after capture and the higher inherent quality captured in a RAW file are some of the reasons commercial photographers shoot in RAW.
