Bits per pixel is a measure of tonal rendering capability in digital pictures. Having 256 possible levels of brightness for each of the colors red, green, and blue can create a good impression of continuous tonal rendering. 256 levels can be represented by an 8-bit (1 byte) binary number, so it takes 3 x 8 = 24 bits to create the impression of continuous tonal rendering. 24 bits corresponds to about 16.7 million possible unique values of hue and brightness. It is better to start with considerably more than 8 bits per color if any image adjustment is to be carried out, so that there will be enough information left to give 8 bits per color in the final result.