Michelsoncontrast

Michelson contrast is a luminance-based measure of the contrast between two regions of a visual scene. It is defined for two luminances, Imax and Imin, as C = (Imax − Imin) / (Imax + Imin). The value ranges from 0 to 1 (often reported as a percentage by multiplying by 100). This metric is especially suited to patterns with periodic or edge-like transitions, such as sine-wave luminance gratings or two-tone images, where Imax and Imin correspond to the brightest and darkest levels.

In practice, Michelson contrast is used in vision science and display engineering to quantify pattern visibility, grating experiments, and the overall contrast performance of displays. It provides a simple, intensity-based descriptor that can be compared across stimuli and viewing conditions. For example, a pattern with Imax = 120 cd/m^2 and Imin = 30 cd/m^2 has a Michelson contrast of (120 − 30) / (120 + 30) = 0.60 (60%).

Limitations of the measure include its assumption of two discrete luminance levels and its lack of direct correspondence with perceived contrast for all stimuli. It may not capture effects of spatial frequency, color, or complex, natural scenes, where other metrics or perceptual models can be more informative.

The concept is named after Albert A. Michelson, reflecting its historical use in studies of optical and visual contrast.