Digital image files are based on tables that list the intensities, or "counts", of all pixels. In case of
RGB images there is one such table for each colour band.
The values are stored in the binary system as 8 or 16 bit numbers; see also Bit Depth. 8 bit monochrome data can be displayed in 28 = 256 greyscales or pseudo-colours, 24 bit RGB data in more than 16 million colours (2563 ). Which pixel count gets which grey value or colour in the image display assigned, is defined in look-up tables or palettes that are edited upon changing the contrast or blanking out background etc.
