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Industrial Vision Systems Based on Application-Specific IC Chips
IEICE TRANSACTIONS on Information and Systems
Publication Date: 1991/06/25
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Image Processing, Computer Graphics and Pattern Recognition
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Some vision systems have been using the same algorithms for many years. These systems usually require high system efficiency at the cost of flexibility for algorithm changes. Various hardware systems dedicated to visual processing applications were developed for high system efficiency. We extended the capabilities of existing binary or gray-level image correlation hardware systems by developing application-specific processor architectures for binary edge correlation. The edge correlation algorithm works well even if the contrast of gray-level image is not good enough for extracting the object with a binary threshold. The binary edge correlation systems require less computational loads compared to typical gray-level image correlation systems. Two types of real-time edge calculation modules have been developed in this project; one for monochrome and the other for color images. The color edge module eliminates edges of shadows by defining discontinuous points of color balances as edges. We developed a different dedicated module for each of correlation, spatial gradient calculation, and edge thinning operations for improving the efficiency of existing general-purpose two dimensional convolution modules. The correlation and image smoothing functions were implemented in application-specific integrated circuit chips. Dedicated boards were developed for the other functions. The binary edge correlation systems (including related modules, such as multi-resolution correlation) have been evaluated in bench tests. The edge calculation portion or the binary edge correlation systems works at frame rates. Bench tests with a slow system clock indicate that the speed of the correlation portion is 1.7102 times faster than a typical microprocessor system with the same system clock speed.