Analog VLSI implementations of receptive field profiles found in visual cortical neurons

Receptive field structures found in the visual cortex of the mammalian brain resemble Gabor filters. There has been recent interest in the use of such receptive field profiles for image coding and texture processing. Systems employing such Gabor filters have been implemented in software for a variety of applications. We believe a hardware implementation of such cells will be helpful in artificial visual processing. We have implemented analog VLSI cells which perform such Gabor-like functions. We describe experimental and simulated results of our circuit. We have implemented both the sine and cosine type of circuits. The sine and cosine circuits described can also be used as edge detection units and on-off center-surround units respectively. Our circuit is the first hardware implementation of a Gabor approximation circuit