Caption: A schematic diagram average human eye luminosity function: i.e., the average human eye of psychophysical sensitivity.
The vertical axis is actually luminous flux (the quantity of psychophysical sensitivity of the human eye with units lumens) per unit power (with units watts).
There are actually two luminosity functions:
Scotopic vision is rather insensitive to color---it's nearly black-and-white vision.
The image is displayed in imcat.php.
Image link: itself.
File: Electromagnetic radiation file:
eye_luminosity_function.html.