EURASIP Journal on Applied Signal Processing 
Volume 2003 (2003), Issue 7, Pages 703-712
doi:10.1155/S1110865703302021

A Vision Chip for Color Segmentation and Pattern Matching

Ralph Etienne-Cummings,1,2 Philippe Pouliquen,1,2 and M. Anthony Lewis1

1Iguana Robotics, P.O. Box 625, Urbana 61803, IL, USA
2Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore 21218, MD, USA

Received 15 July 2002; Revised 20 January 2003

Abstract

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.