Luminous intensity expressed in candelas. The international light commission. Sets many standards. Effect of a light source on the color appearance of objects in comparison with their color appearance under normal daylighting. Cones dominate the response when the luminance level is high, and provide color perception.
Rods dominate at low luminance levels.
No rods are found in the central part of the fovea. Rods have no color perception ability. The inverse square law and the cosine law can be combined. Glare resulting in reduced visual performance and visibility. It is often accompanied by discomfort.