Colour Sensation

The cause of color sensation is the color stimulus, while the effect is the perception of color. According to the physicist Helmholtz, color sensation is defined by hue, saturation, and brightness. In the CIE L*, a*, b* color space, these are represented by the coordinates L* (for brightness), a* (red-green), and b* (blue-yellow), which together define color sensation.
Color sensation describes the specific effect of a light beam on the color receptors in the human eye and is thus a measure of the color perception of that light beam.
In contrast to spectral distribution, which describes the entire composition of the light spectrum, color sensation focuses on the resulting color perception. In colorimetric systems, color sensation is represented as a point in a three-dimensional color space, with colors that have the same color sensation being considered visually indistinguishable.