Pattern recognition method
First Claim
1. A pattern recognition method comprising the steps of:
- detecting a first change in type between two consecutive pixels in a direction of a raster-scan which is carried out for a binary image of an unknown pattern, one of said two consecutive pixels being designated as a start point from which a trace of a contour of said binary image starts;
tracing said contour of said binary image in a predetermined direction along a predetermined type of pixels in such a way that four adjacent pixels on upper, lower, left-hand and right-hand sides of a point of interest are checked in a direction starting from one pixel out of said four adjacent pixels which is positioned on a predetermined side at an angle of 90 degrees with respect to a moving direction in which the trace proceeded towards said point of interest and that one pixel of a predetermined type out of said four adjacent pixels which is first found by checking said four adjacent pixels in said direction is designated as a next trace point subsequent to said point of interest;
extracting a feature of each of the pixels at the traced points which form an image of said contour of said pattern; and
identifying said unknown pattern by comparing said features or said unknown pattern with features of a known pattern.
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Accused Products
Abstract
A pattern recognition method comprises a contour tracing step of a contour of a binary image in a predetermined direction along a predetermined type of pixels. At this time, four adjacent pixels on upper, lower, left-hand and right-hand sides of a point of interest are sequentially checked. Then, one pixel of a predetermined type out of the four adjacent pixels which is the first pixel of the predetermined type found by the check is designated as a next trace point subsequent to the point of interest. In this process, a feature of each of the traced pixels is extracted. The feature is represented by a directional code which indicates a direction of motion from the point of interest to the next trace point. The features are successively registered in a one-dimensional form. Histogram is produced for each sub-region storing a part of the one-dimensional feature sequence. A histogram for each sub-region is compared with a related reference histogram for a known character.
51 Citations
31 Claims
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1. A pattern recognition method comprising the steps of:
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detecting a first change in type between two consecutive pixels in a direction of a raster-scan which is carried out for a binary image of an unknown pattern, one of said two consecutive pixels being designated as a start point from which a trace of a contour of said binary image starts; tracing said contour of said binary image in a predetermined direction along a predetermined type of pixels in such a way that four adjacent pixels on upper, lower, left-hand and right-hand sides of a point of interest are checked in a direction starting from one pixel out of said four adjacent pixels which is positioned on a predetermined side at an angle of 90 degrees with respect to a moving direction in which the trace proceeded towards said point of interest and that one pixel of a predetermined type out of said four adjacent pixels which is first found by checking said four adjacent pixels in said direction is designated as a next trace point subsequent to said point of interest; extracting a feature of each of the pixels at the traced points which form an image of said contour of said pattern; and identifying said unknown pattern by comparing said features or said unknown pattern with features of a known pattern. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A pattern recognition method comprising the steps of:
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detecting a change in type between two consecutive pixels in a direction of a raster-scan which is carried out for a binary image of an unknown pattern, one of said two consecutive pixels being designated as a start point from which trace of a contour of said binary image starts; tracing said contour of said binary image in a predetermined direction along a predetermined type of pixels in such a way that four adjacent pixels on upper, lower, left-hand and right-hand sides of a point of interest are checked in a predetermined rotational direction starting from one pixel out of said four adjacent pixels which is positioned on a predetermined side at an angle of 90°
with respect to a moving direction in which the trace proceeded towards said point of interest and that one pixel of a predeterminted type out of said four adjacent pixels which is first found by said check is designated as a next trace point following said point of interest;extracting a feature of each of the pixels at the traced points which form an image of said contour of said pattern, said feature being a directional code which indicates a moving direction from said point of interest to said next trace point; and identifying said unknown pattern by comparing said features of said unknown pattern with features of a known pattern. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A pattern recognition method comprising the steps of:
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tracing a contour of a binary image of an unknown pattern which is obtained by a raster-scan; extracting a feature of each of pixels at said contour which form an image of said contour of said unknown pattern; registering said feature of each of pixels in a memory region in order of appearance of said feature, so that a one-dimensional code sequence is registered in said memory region; dividing said memory region which stores said one-dimensional code sequence into a plurality of one-dimensional sub-regions, each including a plurality of partial code sequences; calculating a feature quantity for each of sub-regions; and identifying said unknown pattern by comparing said feature quantity for each sub-region of said unknown pattern with a feature quantity for each respective sub-region of a known pattern. - View Dependent Claims (28, 29, 30, 31)
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Specification