NOTE: This definition was changed in RP-16-17 Addendum 4. Deletions have a strike-through. New text is bold.
The minimum perceptible difference in luminance between two areas.
Note: This can apply to the difference between two separated objects on a common background, or the difference between two juxtaposed patches separated by a contrast border, or the difference between a uniform small object and its background. In the last case, the threshold is called contrast threshold.« Back to Definitions Index