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A Vision Chip for Color Segmentation and Pattern Matching


A 128(H) 64(V) RGB CMOS imager is integrated with region-of-interest selection, RGB-to-HSI transformation, HSI-based pixel segmentation, (36bins 12bits)-HSI histogramming, and sum-of-absolute-difference (SAD) template matching. Thirty-two learned color templates are stored and compared to each image. The chip captures the R, G, and B images using in-pixel storage before passing the pixel content to a multiplying digital-to-analog converter (DAC) for white balancing. The DAC can also be used to pipe in images for a PC. The color processing uses a biologically inspired color opponent representation and an analog lookup table to determine the Hue (H) of each pixel. Saturation (S) is computed using a loser-take-all circuit. Intensity (I) is given by the sum of the color components. A histogram of the segments of the image, constructed by counting the number of pixels falling into 36 Hue intervals of 10 degrees, is stored on a chip and compared against the histograms of new segments using SAD comparisons. We demonstrate color-based image segmentation and object recognition with this chip. Running at 30 fps, it uses 1 mW. To our knowledge, this is the first chip that integrates imaging, color segmentation, and color-based object recognition at the focal plane.

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Correspondence to Ralph Etienne-Cummings.

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Etienne-Cummings, R., Pouliquen, P. & Lewis, M.A. A Vision Chip for Color Segmentation and Pattern Matching. EURASIP J. Adv. Signal Process. 2003, 407169 (2003).

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