A 500 x 500 Pixel Image Sensor with Multiple Regions of Interest for Center of Mass-Based Event Detection

This article reports on a 500×500 pixel CMOS vision sensor allowing multiple regions of interest (RoIs) per frame with programmable and arbitrary number, size, and shape, aimed at minimizing the delivered data and at reducing the required amount of off-chip computation. In the proposed application, the center of mass (CoM) terms of the RoIs, computed by the sensor, are used to monitor the activity in some zones of the scene to switch the sensor to a pixel delivering mode, enabling high-level image processing upon request through an external processing platform. Anomalies are detected as changes in the x–y position of the CoM. The embedded CoM processor (CoMP) extracts the centroid terms of the selected subwindows, managing a maximum RoI size of 128×128 pixels. The parameters of each RoI are uploaded rowwise through a serial interface (SI). The sensor with 8- μ m pixel pitch is manufactured in a 110-nm 1P4M CMOS technology and occupies 25 mm2. The chip, operating in standard imaging mode (IM), consumes 4.9 mW at 20 fps.