Abney effect

[1][2] The addition of white light will cause a desaturation of the monochromatic source, as perceived by the human observer.

However, a less intuitive effect of the perceived white light addition is the change in the apparent hue.

This variance of hue as a result of the addition of white light was first described by the English chemist and physicist Sir William de Wiveleslie Abney in 1909, although the date is commonly reported as 1910.

In chromaticity diagrams, a line that has constant perceived hue must be curved, so that the Abney effect is accounted for.

[5] The chromaticity diagrams that have been corrected for the Abney effect are therefore excellent illustrations of the non-linear[clarification needed] nature of the visual system.

and not see a shift in hue, thereby suggesting a straight-line plot for the different levels of mixture would be appropriate on a chromaticity diagram.

Hue and saturation are perceived due to varying amounts of activity in these neural channels consisting of axon pathways from retinal ganglion cells.

The coupling of a faster response with a higher amplitude from the achromatic channel means that reaction time will most likely depend on both the luminance and the saturation levels of the stimuli.

[5] The customary explanations for color vision explain the difference in hue perception as elemental sensations that are inherent to the physiology of the observer.

To this end, both the observer’s spectral sensitivity and the relative number of cone types have proven to not play any significant role in perceiving different hues.

[9] Perhaps the environment plays a larger role in the perception of unique hues than the different physiological features across individuals.

However, the Abney effect describes the change in colorimetric purity by the addition of white light.

[12] A small (< 2 nm) change in wavelength causes most spectral colors to appear to take on a different hue.

He examined the percentage composition and luminosity found in the different spectral colors as well as the white light source that was added.

This variation of bandwidth directly targeted the three classes of cone receptors as a means of identifying any hue shifts as perceived by the human eye.

[14] The overall goal of the research was to determine whether the appearance of color was affected by the filtering effects of the spectral sensitivity of the eye.

Ultimately, the researchers came to the conclusion that variations in spectral bandwidth cause postreceptoral mechanisms to compensate for the filtering effects imposed by cone sensitivities and preretinal absorption and that the Abney effect occurs because the eye has, in a sense, been tricked into seeing a color that would not naturally occur and must therefore approximate the color.

This approximation to compensate for the Abney effect is a direct function of the cone excitations experienced with a broadband spectrum.