Patent ID: 6266445
Filing Date: 2001-07-24
Classification: G06K

Abstract:
In an image recognition system, a method for recognizing a sample image comprising a plurality of pixels from a set of binary referent images, each pixel of the sample image comprising a multi-bit value, the method comprising:normalizing the size of the sample image to the size of the referent images; anddetermining a set of candidate images from the set of referent images, wherein each of the candidate images is within an acceptable distance from a different binarization of the sample image, by performing the following substeps for each referent image:determining a range of binarization thresholds for the sample image,creating a binarization of the sample image using a selected binarization threshold in the range by setting those pixel values of the sample image greater than the threshold to one of two values, and setting those pixel values of the sample image less than or equal to the selected threshold to another of the two values,calculating a distance between the selected referent image and the binarization of the sample image for the selected binarization threshold, andresponsive to the distance being acceptable, selecting the referent image as a candidate in a set of candidate images for the sample image, andresponsive to the distance being unacceptable, selecting another binarization threshold in the range, and repeating the creating, calculating, responsive to the distance being acceptable, selecting the referent image as a candidate, and responsive to the distance being unacceptable, selecting another binarization threshold in the range substeps until the range of thresholds for the referent image is exhausted.