A Spatial-Temporal Multiresolution CMOS Image Sensor With Adaptive Frame Rates for Tracking the Moving Objects in Region-of-Interest and Suppressing

Abstract

In this paper, we report a CMOS image sensor for spatial-temporal multiresolution images. This image sensor simul- taneously generates two outputs: one for normal images ( 30 fps) of stationery background and the other for adaptable frame-rate images (over 960 fps) of moving objects. The moving objects are tracked with a reduced spatial resolution in the region-of-interest (ROI). The entire image is reconstructed from the two images with the details in stationery objects and the suppressed motion blur in moving objects. High frame rate only applies to the ROI; therefore, the proposed scheme can significantly reduce power consumption by adjusting the optimal use of bandwidth. In order to provide real-time decision of ROI, the sensor employs on-chip motion-detection circuits based on the inter-pixel switch operation by storing the previous frame signal in a floating diffusion node. This allows a small pixel implementation without adding any extra in-pixel memory components. A prototype chip has been implemented using a 0.35 m 1P4M standard CMOS process and multiresolution images have been successfully captured. The fabricated chip operates at 3.3 V and consumes 75 mW in the multiresolution readout of a 256 256 normal image at 30 fps and a6 4 64 ROI image at 240 fps.