This investigation examines the effects of having a light or dark surround around a color; in particular, the effect these surrounds have on the perceived saturation of the color. The results of the experiments show that a dark surround not only increases the apparent brightness of a color but also reduces its apparent saturation. That is, for equivalence with a light-surrounded color, a color with a dark surround must have a higher purity.
I. T. Pitt and L. M. Winter, "Effect of surround on perceived saturation," J. Opt. Soc. Am. 64, 1328-1331 (1974)