Contrast or more appropriately put the contrast ratio of a liquid crystal display is the ratio of the light area of a display to the dark area. For a reflective display this is the ratio of the light reflected by the background to the light absorbed by the rear polarizer of any on segment. Stating the contrast ratio is easy, measuring it is not. The contrast ratio will change with the angle and position around the display. As illustrated by the isocontrast plot of a first minima display below, the contrast ratio changes as one tilts away from normal and rotates the display about 360 degrees.

Direct drive displays have excellent contrast over a wide range of viewing directions. Because of the drive scheme used for multiplexed displays, the viewing angle and contrast ratio begin to change more rapidly than direct drive displays, and it becomes important for the user to know how the display will be viewed in the instrument.

Also, see What is a viewing angle? in the FAQ section for related information.