A row-parallel cyclic-line-access edge detection CMOS image sensor employing global thresholding operation

An edge detection CMOS image sensor employing global thresholding operation has been developed. A cyclic-line-access computation scheme has enabled seamless directional edge filtering in the row-parallel manner. The global thresholding algorithm adaptively determines the threshold value by taking the entire intensity distribution in the image into account and allows us to extract more significant features from input images autonomously. An analog proof-of-concept chip for four-directional edge detection was designed and fabricated in a 0.18-μm single-poly 5-metal CMOS technology. This chip carries out four-directional edge filtering by taking the convolution of 5×5-or 5×7-pixel kernels, and determines whether the edge exists or not by global thresholding. The concept has been experimentally verified by the measurement of fabricated chips.