Difference between the brightest whites and the darkest blacks on a display. Generally, the larger the contrast ratio the greater the ability of a projector to show subtle color details and tolerate extraneous room light. However, there are limits to what the human eye will discern in terms of differences in contrast ratio.
The difference between the light intensity of the brightest and darkest possible tones a display can reproduce. The greater the difference, the sharper the display. For instance, 10,000:1 provides a supercrisp picture.
This is the ratio of the brightness between the lightest and darkest areas in a subject.