What to Look for Color depth, for lack of a better term, is the size of the data that are internally manipulated by the scanner for each dot read. Remember, I said that this was the number of bits used internally by the hardware. That is all this means. Nothing more Most importantly, color depth does not mean how many colors the scanner can resolve. See optical density below.
Optical density represents the range of color tonal values that the hardware can resolve.
Obviously, the more discrete colors that the scanner can recognize, the more accurate the scanned image can be. Optical density is a logarithmic scale, so small increases are more significant than normal. This may be the single most important indicator of a scanner s quality. Of course, you probably won t be able to find this value in the specifications of most flatbed scanners. Scanners offer a wide range of resolutions in advertisements.