A silicon retina for computing local edge orientations

Carver Mead has demonstrated the suitability of VLSI arrays of photoreceptors and analog CMOS processing circuitry (so-called silicon retinas) for doing early vision processing. So far, chips have been built that perform center-surround (X-system) and motion detection (Y-system) operations. This Paper describes a chip which was designed to perform a low level of image feature extraction: orientation selectivity.