A multi-stage model for border contrast.

A multi-stage model has been constructed. In this model, the first level is expressed by a convolution of the physical luminance function with a line spread function whose parameters depend on luminance. The second level extracts the gradient of the response that is processed at the first level. The third level detects, as edges, the inflection points of the response that is processed at the first level. The fourth level averages the response gradients over each interval between the edges, while keeping the total magnitude of the final response within the interval the same as those of the initial response at the first level. The model was applied to border contrast phenomena as described by Bergström (1966).