Brightness is an attribute of visual perception in which a source appears
to be radiating or reflecting light. In other words, brightness is the
perception elicited by the luminance of a visual target. The perception is not
linear to luminance, and relies on the context of the viewing environment (for
example, see White's illusion).
Brightness is a subjective sensation of an object being observed and one of
the color appearance parameters of many color appearance models, typically
denoted as Q {\displaystyle Q} . Brightness refers to how much light appears
to shine from something. This is a different perception than lightness, which
is how light something appears compared to a similarly lit white object.