Human Systems Integration Division @ NASA Ames

We have implemented a model of contrast gain control in human vision which incorporates a number of key features, including a contrast sensitivity function, multiple oriented band-pass channels, accelerating nonlinearities, and a divisive inhibitory gain-control pool. The parameters of this model have been optimized through a fit to the recent data that describe masking of a Gabor function by cosine and Gabor masks [Foley, J. M. (1994). Human luminance pattern mechanisms: masking experiments require a new model. Journal of the Optical Society of America A 11(6), 1710-1719]. The model achieves a good fit to the data. We also demonstrate how the concept of recruitment may accommodate a variant of this model in which excitatory and inhibitory paths share a common accelerating non-linearity, but which include multiple channels tuned to different levels of contrast [Teo, P. C. & Heeger, D. J. (1994). Perceptual image distortion . Proceedings, ICIP-94, Austin, Texas, IEEE Computer Society Press, II, pp. 982-986].