The study of visual quality

Contrast Sensitivity is a diagnostic test which allows us to judge the ability of a person to identify an object and separate it from the background in which it is to be found.

Contrast sensitivity is different to visual acuity in that it permits us to measure the quantity as well as the quality of vision.
Contrast sensitivity is evaluated using special evaluation tables , such as the ECAF table, which can be used for checking visual acuity when projected onto a wall.