Application of fourier analysis to the visibility of gratings

TLDR

The results are explained by linearly operating, frequency‑selective mechanisms in the nervous system. Contrast thresholds for various grating waveforms across spatial frequencies depend solely on the amplitude of the fundamental Fourier component, and complex waveforms become distinguishable only when higher harmonics reach their thresholds. 1.

Abstract

1. The contrast thresholds of a variety of grating patterns have been measured over a wide range of spatial frequencies.2. Contrast thresholds for the detection of gratings whose luminance profiles are sine, square, rectangular or saw-tooth waves can be simply related using Fourier theory.3. Over a wide range of spatial frequencies the contrast threshold of a grating is determined only by the amplitude of the fundamental Fourier component of its wave form.4. Gratings of complex wave form cannot be distinguished from sine-wave gratings until their contrast has been raised to a level at which the higher harmonic components reach their independent threshold.5. These findings can be explained by the existence within the nervous system of linearly operating independent mechanisms selectively sensitive to limited ranges of spatial frequencies.