Simulated Retinal Center/Surround Artificial Neuroprocessing Using Analog VLSI
We designed an array of CMOS circuits to realize part of a model of a biological retina that acts as a preprocessing stage in a Boundary Contour System/Feature Contour System1. The basis for the circuitry is a shunting neuron equation. The “membrane” voltage of this silicon neuron hyperpolarizes as a function of the surround excitation and depolarizes as a function of the center excitation. The electronics approximates a Difference of Gaussians operator for edge enhancement. That quantity is scaled by an approximation to a Sum of Gaussians operator. Thus, the output reports on contrast that is normalized by the image’s absolute intensity in a local region.
KeywordsSynthetic Aperture Radar Synthetic Aperture Radar Image Boundary Contour Edge Enhancement Tonic Level
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