Local contrast used by Paul Signac in Quay at Clichy 1887
46.4 x 65.4 cm Oil on canvas The Baltimore Museum of Art, Baltimore, Gift of Frederick H. Gottlieb
downloaded from https://www.pubhist.com/w15231
The point of this webpage is to show that Signac intentionally changed values of areas that we would consider uniform for the purpose of increasing contrast of neighboring areas.
Could be ambitious and say there is a mathematical fit, such as in the red channel this fit to exponential decay of intensity by distance as stepping away from the dark object.