Dynamic range is the ratio of contrast, tonal range or density in an image between black and white. The number 0.0 represent white and black is 4.0. A flatbed scanner may have a dynamic range of 2.4-2.7 while a drum scanner may be as high as 3.6-3.8. The numeric ranges stated is the ability of the device to record and reproduce the range of grays between black and white. The higher the number the greater the detail in shadow (black) and highlight (white) reproduced in an image.