A 256×256 pixel smart CMOS image sensor for line-based stereovision applications

摘要

This paper presents a 256×256 pixel smart CMOS image sensornfor line based vision applications. By combining the edge-based analognprocessing technique with an active pixel array, a dense and fastnon-chip analog image processing has been achieved. The on-chipnprocessing unit includes (1) an analog histogram equalizer, (2) anprogrammable recursive Gaussian filter, (3) a spatio-temporalndifferentiator, and (4) a local extrema extractor. An electronic shutternis applied to the active pixel sensor array in order to adapt thenexposure time as a function of global illumination. The on-chipnhistogram equalizer extends the image into a constant and optimal rangenfor all the following processing operators and gives a stable andnpredictable precision of the analog processing. A prototype chip hasnbeen designed and fabricated in a standard 0.8-Μm CMOS process withndouble poly and double metal, giving a pixel pitch of 20 Μm and diensize of 7×7 mm2. A line processing time is compatiblenwith TV line scan period. The worst case power consumption measures 40nmA at 5 V