Abstract
It has been shown that perceived colorfulness changes with adaptation to chromatic contrast modulation and to surrounding chromatic variance. It is still not clear how colorfulness perception changes with adaptation to color variations in actual environments or natural images, and mechanisms contribute to the perception. We have showed that the impression of an image was less colorful after explosion to saturated images and vice versa (APCV 2010). The effect was weaker when jumbled images were used for adaptation instead of natural images. Here, we examined how the effect of colorfulness-adaptation changes depending on adapting images, especially in relation to image recognition. The different types of image-sets were used as adaptation images; natural images consisting of natural scene or objects, jumbled images consisting of the collage of randomized color blocks cut from original images with different segmentation levels (5 by 5, 10 by 10, and 20 by 20 blocks). Five saturation-levels were examined for each image-set. A test image, which was not included in the adaptation images, was prepared for colorfulness judgment. An observer adapted to a series of images, which appeared randomly for 2 minutes, and then judged a test image at one of the eleven saturation levels. The judgment whether the test image was colorful or not was made each time a test image was presented following to 6 seconds re-adaptation. The method of constant stimuli was used. The results showed that colorfulness perception was changed by adaptation to the levels of image saturation in both natural and jumbled images. The effect was stronger with adaptation to natural images than with jumbled images. Although the effect for the different jumbling levels was different in each observer, it was generally weaker for the images with smaller blocks, implying that a colorfulness-adaptation mechanism worked better with natural images including recognizable scenes.