Abstract

We model pattern masking with a retinal luminance adaptation process followed by orientation-selective cortical filtering. We analyzed threshold elevations of a bandpass test stimulus (a 33 ms D6, sixth derivative of a Gaussian) masked by a 433 ms cosine grating, varying test polarity and spatial phase of the mask. The retinal process was defined by threshold elevation on uniform fields of the same luminance as the peak and the trough of the mask. The cortical process was defined by dividing cosine threshold elevation by uniform field elevation. The retinal process can be modeled with a Naka-Rushton nonlinearity. The cortical process is phase dependent, with threshold elevation greatest for negative tests on light bars and positive tests on dark bars of the mask grating. For the cortical process, dark bars produce more masking than light bars. We conclude that the cortical process must involve competitive interaction between on and off systems.

© 1992 Optical Society of America