A model has been developed of how the threshold contrast of the visual system depends on the external conditions, based on the tremor modulation signal. The model is tested on experimental arrays of the threshold perception of disks, sinusoidal and rectangular grids, the Ricco and Piper laws for spatial summation, and the Bloch–Charpentier and Blondel–Rey laws for the temporal summation of the signal. It is shown that the results converge. The proposed model describes the dependence of the perception threshold on the adaptation brightness, the angular size of the stimulus, and the time that the stimulus is presented. For a specific shape of the stimulus, the model has a simple analytical expression that contains no correction factors or functions, and this makes it convenient for carrying out illumination-engineering calculations and calculating the operating range of optical and optoelectronic devices. A physiological treatment of the model correlates with the selective organization of the sections of the visual cortex.
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