The retinomorphic approach: Pixel-parallel adaptive amplification, filtering, and quantization

I describe a vision system that uses neurobiological principles to perform all four major operations found in biological retinae: (1)continuous sensing for detection, (2) local automatic gain control for amplification, (3) spatiotemporal bandpass filtering for preprocessing, and (4) adaptive sampling for quantization. All four operations are performed at the pixel level. The system includes a random-access time-division multiplexed communication channel that reads out asynchronous pulse trains from a 64 x 64 pixel array in the imager chip, and transmits them to corresponding locations on a second chip that has a 64 x 64 array of integrators. Both chips are fully functional. I compare and contrast the design principles of the retina with the standard practice in imager design and analyze the circuits used to amplify, filter, and quantize the visual signal, with emphasis on the performance trade-offs inherent in the circuit topologies used.