On the appearance of Mach bands in gradients of varying color

Abstract

Red and green triangular-wave intensity distributions were generated on cathoderay oscilloscope tubes. When these patterns are viewed separately, light and dark Mach bands appear at the peaks and troughs of the intensity distribution. The perceived brightness distribution was quantified by matching the brightness of the pattern with a narrow slit of light of the same color positioned in varying positions just below the triangular-wave field. The sensations produced by gradients of color rather than luminance have been investigated by interlacing equiluminous red and green triangular gratings 180[deg] out-of-phase (dark bands in one field correspond to bright bands in other field). An illuminated slit just below the chromatic gradients was adjusted in color and brightness to produce satisfactory matches to different parts of the interlaced red and green patterns. Our measurements show that bright red and green bands appear in light distributions of constant luminance and varying chromaticity.