Display Contrast - Luminance Contrast

Luminance Contrast

The "luminance contrast" is the ratio between the higher luminance, L_H, and the lower luminance, L_L, that define the feature to be detected. This ratio, often called contrast ratio, CR, (actually being a luminance ratio), is often used for high luminances and for specification of the contrast of electronic visual display devices. The luminance contrast (ratio), CR, is a dimensionless number, often indicated by adding ":1" to the value of the quotient (e.g. CR = 900:1).

with 1 ≤ CR ≤

A "contrast ratio" of CR = 1 means no contrast.

The contrast can also be specified by the contrast modulation (or Michelson contrast), C_M, defined as:

with 0 ≤ C_M ≤ 1.

C_M = 0 means no contrast.

Another contrast definition sometimes found in the electronic displays field, K, is:

with 0 ≤ K ≤ 1.

K = 0 means no contrast, the maximum possible contrast, K_max equals one.