Vision Chip Architecture for Detecting Line of Sight Including Saccade

SUMMARY Rapid eye motion, or so called saccade, is a very quickeye motion which always occurs regardless of our intention. Althoughthe line of sight (LOS) with saccade tracking is expected to be used fora new type of computer-human interface, it is impossible to track it usingthe conventional video camera, because of its speed which is often up to600 degrees per second. Vision Chip is an intelligent image sensor whichhas the photo receptor and the image processing circuitry on a single chip,which can process the acquired image information by keeping its spatialparallelism. It has also the ability of implementing the very compact inte-grated vision system. In this paper, we describe the vision chip architecturewhich has the capability of detecting the line of sight from infrared eye im-age, with the processing speed supporting the saccade tracking. The visionchip described here has the pixel parallel processing architecture, with thenode automata for each pixel as image processing. The acquired image isdigitized to two flags indicating the Purkinje’s image and the pupil by com-parators at first. The digitized images are then shrunk, followed by severalsteps of expanding by node automata located at each pixel. The shrinkingprocess is kept executed until all the pixels disappear, and the pixel dis-appearing at last indicates the center of the Purkinje’s image and the pupil.This disappearing step is detected by the projection circuitry in pixel circuitfor fast operation, and the coordinates of the center of the Purkinje’s imageand the pupil are generated by the simple encoders. We describe the wholearchitecture of this vision chip, as well as the pixel architecture. We alsodescribe the evaluation of proposed algorithm with numerical simulation,as well as processing speed using FPGA, and improvement in resolutionusing column parallel architecture.