These variations are represented in a scale of values ranging from 0 to 255 with 0 having the least intensity and 255 having the greatest. When the 3 components are combined there are 256 x 256 x 256 possible combinations or 16,777,216 possible colors. CMYK images are derived from the 3 primary colors of cyan, magenta and yellow plus black. In 32-bit CMYK color, each cyan, magenta, yellow and black component is also 8 bits long and has 256 variations in intensity. Each pixel in a 32- bit CMYK image is one of 256 x 256 x 256 possible colors x 256 variations of black.
Many graphics programs support both color models.
The color palette of an indexed color image has a fixed number of colors. Hence, they are not true color. Some file formats restrict the number of colors to fewer than 256 . The GIF format is one such format and has a color depth of 8 bits per pixel or less. GIF files use indexed color and allow a maximum of 256 colors.