Dynamic Range
If you are faced with two scanners that match each other in bit depth, resolution, and price, dynamic range may set one apart from the other. Dynamic range is similar to bit depth in that it measures the ability of the scanner to reproduce tones. It is measured on a scale from 0 to 5, with 0 representing absolute white and 5 representing absolute black.

Most standard color flatbeds have a dynamic range between 2 and 2.5. Unless you need to have perfect color reproduction, this amount should meet your scanning needs. Higher end flatbeds can get up near 3, after which professional drum scanners are needed for exact prepress reproductions.

While dynamic range should not be thought of as a straight grade of a scanner's ability, it is a useful tool for comparing scanners with similar specifications.