Noun
color depth (countable and uncountable, plural color depths)
(computer graphics) The number of bits per pixel used to store color information in an image.
Some programs - especially games - require that your system be set to a particular color depth and resolution. Often such special settings are different from your usual mode, though. Charles Petzold
Having a color range that exceeds the content is a useless feature. citation * Color depth or color support is sometimes expressed in bits, either as the number of bits per sub-pixel or the number of bits per pixel. Source: Internet