Illumination uniformity assessment based on human vision.

Assessing how uniform the light distribution is throughout an illuminated target is important in many applications, but traditional methods do not quantify the variability of illuminance as the human visual system (HVS) does. Considering that most light patterns are intended for humans, I propose a simple metric that assesses the uniformity in a similar way as humans do. This uniformity indicator is based on the fact that the HVS is highly sensitive to spatial frequencies and then uses the Fourier transform and the contrast sensitivity function of the HVS in a practical way.