Diagram: Comparison of Krita's Desaturate Filter Methods

A comparison of Krita's desaturate filter algorithms using a photo of a rainbow. A notable differences: compared to the default "lightness" algorithm, "luminosity" will make greens and yellows lighter grays. In a rainbow, all colors are saturated, which means, for example, the pure red would be toward a 255, 0, 0 RGB tuple. In this tuple, "maximum" is 255, while the minimum is 0, which is why saturated colors become black (0, 0, 0) with the "minimum" algorithm, and white (255, 255, 255) with the "maximum" algorithm. The "average" made the rainbow disappear as the colors only changed in hue.

Photo by JOHN K THORNE on Flickr.