Bezold–Brücke shift

Both Bezold & Brücke worked on the Bezold-Brücke effect and gave important contributions in the field of optical illusions.

In the Abney effect, hue shifts ocurr when linearly mixing a color and white.

This effect is a problem for simple HSV-style color models, which treat hue and intensity as independent parameters.

In contrast, color appearance models try to factor in this effect.

The shift in the hue is also accompanied by the changes in the perceived saturation.

As intensity increases, spectral colors below 500 nm (greenish cyans, cyans, and violets) shift towards blue, spectral colors above 500 nm (reds, oranges, and greens) shift towards yellow
The colors on the left have the same chromaticity as their respective color on the right, with the only difference being the brightness. With cyan, it can be seen that increasing the brightness shifts the hue towards blue; with orange, it shifts towards yellow; and with violet, it shifts towards blue.