Chromatic Flicker*

Abstract

A color-television monitor with some peripheral equipment is used as an appropriate device for generating stimuli of different wave forms. The chromaticity of the screen is alternated sinusoidally in time around a fixed yellow reference color. The chromatic fusion point depended on the magnitude of the chromatic differences of the flickering components. The critical color flicker frequency ccff as a function of the chromatic contrast in the stimulus is determined at seven retinal illuminances between 220 and 0.5 td. Even at the highest illuminance, none of the characteristics showed any resonance qualities, as is a well-known phenomenon in the de Lange curves on brightness flicker. Two main relationships are deduced from the records. First, the variation of the ccff with the logarithm of the illuminance F=a logI+b, as formulated in the Ferry–Porter equation; Second, the dependence of the chromatic threshold contrast ΔC on retinal illuminance, ΔC=kI-12. This relationship is predicted by the fluctuation theory of visual threshold behavior, which takes into account the essentially random numbers of incident photons on the retina. Using sine, square, and triangular waveforms it is demonstrated that the contrast-transmission system for chromatic flicker operates practically in a linear manner up to a ccff of 7 Hz.