Influence of naturalness of chroma and lightness contrast modulation on colorfulness adaptation in natural images.

We investigated as to whether the naturalness of images modulated by a combination of chroma and lightness contrast affects the colorfulness perception. Four types of modulated images with different combinations of chroma and lightness contrast were used as adaptation stimuli. After adapting to one of the adaptation stimuli groups, observers judged the colorfulness of test images that were also modulated by the different combinations of chroma and lightness contrast. Our results showed that the combination of chroma and lightness contrast modulation affected the strength of colorfulness adaptation. The results also indicated that when adapting to images that exhibited high naturalness, the effect of colorfulness adaptation was strong. It was suggested that the naturalness of the chroma and lightness combination is an important factor for colorfulness adaptation.