H. Deridder, NATURALNESS AND IMAGE QUALITY - SATURATION AND LIGHTNESS VARIATION INCOLOR IMAGES OF NATURAL SCENES, Journal of imaging science and technology, 40(6), 1996, pp. 487-493
The relation between perceived image quality and naturalness was inves
tigated by varying the colorfulness of natural images at various light
ness levels. At each lightness level, subjects assessed perceived colo
rfulness, naturalness, and quality as a function of average saturation
by means of direct category scaling. Colorfulness was found to increa
se monotonically with average saturation. The relation between the qua
lity/naturalness judgments and average saturation could always be desc
ribed by an inverted U-shaped function. A systematic difference was fo
und between quality and naturalness judgments. This difference, reflec
ting the subjects' preference for more colorful, but, at the same time
, somewhat unnatural images, was most noticeable at the original light
ness level and diminished with decreasing lightness, in particular bei
ng least at the lowest lightness level investigated.