About
Brightness is:
- a subjective attribute of light
- a perception
Brightness is also known as lightness
It cannot be measured objectively (but can be scaled, e.g. in %).
The perception:
- is not linear to luminance,
- relies on the context of the viewing environment.
For instance, a monitor can be adjusted to a level of light between very dim and very bright.
The inverse of brightness is dullness.
Formal definition
The brightness is:
- the value of an area judged
- relative to the brightness of a similarly illuminated area that appears to be white (ie highly transmitting).
It is then the representation of variation (relative) in the perception of a color or color space's brightness.