Figure 1.

The equiluminant plane of the MacLeod-Boynton chromaticity space showing chromaticities used in the experiments. Circles at the ends of a single line represent chromaticities of the square wave modulation used in the experiments (always symmetric around equal-energy-spectrum “white” at the center of the diagram). Four axes of chromatic modulation are shown. The vertical and the horizontal axes are referred to as cardinal axes (Derrington et al., 1984). The two diagonals are referred to as intermediate axes.