Luminance and chromaticity conditions of a bichromatic cross pattern for chromatically-uniform transparency

We can perceive a surface through another surface. This perception is calle d transparency. It is known that transparency can be perceived even if the stimulus conditions are not consistent with physical conditions for a real transparent surface. In this study, we measured the ranges of luminance and chromaticity of the overlapping area of two crossed layers at which a surf ace was perceived as chromatically-uniform transparent. As the results, the luminance range of the overlapping area existed around or near the luminan ce of the inducing area. The upper and lower limits of the luminance range were higher for the dark background than for the light background. Moreover , the chromatic range existed around the additive color-mixture line betwee n two chromaticities of the inducing areas for both dark and light backgrou nds. This indicates that the perceptual transparency mechanism would divide the color of an additive color mixture into the original colors that exist in the inducing areas. We noticed that the perceptual appearance of the st imulus changed greatly depending on the luminances of the overlapping area and the background. These differences in perceptual appearance would be a f actor explaining individual difference and deciding the luminance condition s for transparency.