Transparency is defined as perception of a surface through another surface as overlapping layers. The physical transmittance of a surface could not be a constraint factor for the transparency perception. In this study. we measured the chromatic and the luminance ranges of the overlapping area of two cross surfaces in order to see transparency. The results show that the additive mixture of colors of the inducing surfaces can be a better constraint factor for transparency. But the luminance of the overlapping area turned out not to be the sum of the inducing surfaces.