Lenses may be used to reduce the effective size of larger originals to fit the CCD array dimensions, thereby reducing the maximum capture resolution. Dynamic range is a logarithmic measure of the sensitivity of the scanning sensor, especially in the shadow areas. Product specs can be given in terms of Dmax or dynamic range. The starting point may not be 0.0, so the Dmax can be higher than the range. The number is a representation of the point above which the sensor reads all shadow details simply as black.
Color depth is another measure of a scanner's image quality.
Greater depth gives operators increased control over the appearance of final images by allowing them to determine how the data is sampled. Image area has an obvious impact on the buying decision. Advances in technology have greatly narrowed the gap, though. RGB to CMYK conversion can be a factor in the buying decision for volume production scanners.