On the number of intensity levels discriminated in textures.

The number of intensity levels detected in briefly displayed textures was studied as a function of two related spatial parameters: granularity and spatial frequency. A texture-discrimination paradigm was used to determine the discriminability of an original texture and of a version of it reduced (further "quantized') in intensity levels over a range of texture granularities and frequency bandwidths. Results show specific sensitivities to intensity level reductions as a function of the spatial-frequency composition of the textures, with particular loss of sensitivity in the higher spatial-frequency regions.