The Hunt effect or Luminance-on-colorfulness effect[1] comprises an increase in colorfulness of a color with increasing luminance.
The effect was first described by RWG Hunt in 1952.
[2] Hunt noted that this effect occurs at low luminance levels.
At higher luminance, he noted a hue shift of colors to be more blue with higher luminance, which is now known as the Bezold–Brücke effect.
The Hunt effect is related to the Helmholtz–Kohlrausch effect, where a saturated stimulus is seen to be brighter than less saturated or achromatic stimuli.