The luminosity curve describes the spectral light sensitivity of the human eye in daylight ( photopic range).
It was determined empirically, 1924 in the "International Standard Observer " published ( International Commission on Illumination, Commission Internationale de l' Eclairage, CIE) and 1983 in the CIE (CIE 018.2-1983 ) revised. Defined 360 nm to 830 nm in 1 nm steps for a 2 ° standard observer in the area. The values of are thus only valid for an observation at an angle of 2 °, which corresponds to the central area of sharp vision in humans. In Germany it is standardized under DIN 5031.
The spectral brightness sensitivity defines the spectral range, which we refer to as light. Together with the photometric radiation equivalent at the maximum of the curve connects the radiant power ( watt unit, range radiometry ) the luminous flux ( lumen unit, field photometry).
For twilight vision ( mesopic range ), the curve and for night vision ( scotopic range) the curve defined. This gain, for example, under the glare rating in automobile headlights in the dark more and more important. The spectral shift between day and night vision is called the Purkinje effect.
The light sensitivity of the human eye is in focus of the terrestrial solar spectrum. Probably also an embossed of plants, green environment plays a role. In particular, in the moonlight and in ( algae- rich ) water is the blue-green spectral range of meaning. The eyes of mammals resemble those of humans. However, the color vision of animals is poorly understood.
However, birds and insects can see particularly in the violet and even in the near ultraviolet spectral range.
Sehempfindlichkeits cell types of humans and animals: trichromatic, Tetrachromat, rods (eye), cones (eye).