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Image inspection/recognition method, method of generating reference data for use therein, and apparatuses therefor

  • US 5,638,465 A
  • Filed: 06/09/1995
  • Issued: 06/10/1997
  • Est. Priority Date: 06/14/1994
  • Status: Expired due to Fees
First Claim
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1. An image inspection/recognition method comprising the steps of:

  • (1) obtaining feature images of predetermined plural features each of a plurality of training images;

    (2) quantizing feature values at respective feature points of the feature images with a predetermined quantization step;

    (3) obtaining a histogram of feature values of the quantized feature images of each of said plural features at each of the respective feature points;

    (4) determining weights for respective feature points of each of said plural features based on the feature value histograms to define reference data of each of said plural features having the weights at the respective feature points;

    (5) extracting an image feature of at least one of said plural features from an input image to form a feature image of the input image;

    (6) quantizing feature values at respective feature points of said feature image of the input image with the predetermined quantization step to obtain a quantized feature image of the input image; and

    (7) calculating the similarity or difference at respective feature points between said quantized feature image of the input image and the reference data of each of said plural features and combining the similarity or different for said plural features with one another with predetermined feature weights to produce weighted similarity or difference;

    said step (7) comprising obtaining weighted difference by subjecting said quantized feature image of the input image to a weighted Hough transform operation by voting the weights of said feature points in said reference data to a parameter space of positions for each quantized level to obtain a Hough plane and calculating the difference between said Hough plane and a reference Hough plane obtained from said quantized feature images of said training images.

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