What is RAW?
Image Format DescriptionRAW image files are what may be called “digital negatives”. They are raw unprocessed data from the image sensor of a digital camera or image scanner, that serve the same purpose as a film negative in chemical photography.
All digital cameras have imaging chips, which are either CCD or CMOS. When a picture is taken with a digital camera, the imaging chip records the amount of light exposed to the camera photo site as a voltage level. The camera analog then changes this voltage level to a digital representation. Depending on the camera type, either 12 or 14 bits of data is recorded. A camera that records 12 bits of data can handle 4,096 brightness levels; and that which can record 14 bits of data can handle 16,384 different brightness levels. This is in sharp contrast to JPEG’s 8 bit space with just 256 brightness levels.
It is not easy to correctly give a description of a RAW image file format, as each camera manufacturer uses its own proprietary RAW format. For example Nikon uses its own NEF RAW format, and Canon its CRW image RAW format. Different manufacturers do this in order to make their files inaccessible to other manufacturers, thus protecting them. But this creates a problem – as not all formats can be read by all applications and operating systems.
RAW files can store a lot of information, even subtle ones like variations and ranges in color and detail. As a result, when exposure to an under-exposed image is increased, the artifacts are less visible than when done from already rendered image files. This allows for more scope for corrections and manipulations. Photo quality may also be improved by tweaking the camera settings for white balance, color saturation, contrast, and sharpness.
The best part about saving images in RAW files is that once all the metadata is saved, whether by compression or otherwise, they contain more information than the converted results, and above all, always remains exactly as saved.
Wit of the daySir, when their backsides look good enough to slap, there's nothing more to do.