Abstract
The chromatic distributions of natural scenes are biased in a blue-yellow direction (Nascimento et al., 2002, JOSA A, 19(8), 1484–1490). Existing research suggests a possible link between natural scene statistics and color discrimination (e.g., Bosten et al., 2015, J. Vis, 15(16), 5). Here we investigate the impact of short-term adaptation to natural and color-reflected images on color perception. In Experiment 1 we measured color discrimination ellipses. In Experiment 2 we measured perception of ‘chromatic balance’ of a distribution of colors. To capture the ‘chromatic diet’ of our participants, we used head-mounted, color-calibrated GoPro cameras to collect images of typical local outdoor scenes. From these images we created two sets of adapting images. The chromaticities of one set of ‘natural’ images were reflected through the S/(L+M) axis of the MacLeod-Boynton chromaticity diagram to create a second set of ‘color-reflected’ images. In both experiments, participants adapted to natural and color-reflected images in separate blocks. In Experiment 1 we measured color discrimination thresholds along 8 hue axes using 4AFC. In Experiment 2 the stimuli were chromatic 1/f noise patterns with constant 1/f luminance noise. The chromaticities of each pattern were distributed elliptically along 1 of 8 color directions in the MacLeod-Boynton chromaticity diagram and had 1 of 4 levels of chromatic bias (ellipse elongation). Participants performed a paired comparison task selecting patterns that appeared to contain more colors and where all the colors were evenly present. Results of Experiment 1 showed that adaptation to colour-reflected scenes changes the elongation of color discrimination ellipses (BF₁₀>1x10^7): after adapting to natural images participants showed higher thresholds for blue and yellow. Results of Experiment 2 showed that after adapting to natural images participants tended to select noise patterns biased in the blue-yellow direction as chromatically balanced. This bias was reduced after adapting to color-reflected images.