Image sensor method and apparatus having hardware implemented edge detection processing

Abstract

An image sensor comprising an integrated circuit chip that includes both a pixel array and edge detection circuitry hardwired together on the chip. The pixel array provides an addressable, non-destructive readout of the pixel data, with the edge detection circuit providing a hardwired implementation of a pair of n×n masks that are convolved with the pixel array data to thereby generate horizontal and vertical edge data that is combined together and outputted by the image sensor. The masks are implemented as a pair of one-dimensional filters, with one of the filters being a one-dimensional Gaussian filter used to smooth the pixel data along one axis and the other filter providing a first derivative Gaussian function to detect edges along the other, orthogonal axis. The non-destructibility of the readout from the pixel array eliminates the need for buffering large amounts of pixel data and the use of separable, one-dimensional filters permits each mask to be implemented using only n simultaneous outputs from the array, 2weights, and n−1 buffers for temporary storage of the smoothed pixel data.