System for reading data glyphs
First Claim
Patent Images
1. A method of locating a glyph on a document, where the glyph contains symbols positioned in a grid of rows and columns, the method comprising:
- scanning the document to acquire at least one image of at least part of the document;
preparing a one-dimensional kernel function having a strong correlation response when aligned with a one-dimensional projection of a glyph;
computing a one-dimensional projection over at least part of the image, where the at least part of the at least one image includes at least part of the glyph;
correlating the one-dimensional projection with the kernel function, where the kernel is located at a selected position in the projection;
repeating the step of correlating for a plurality of relative positions of the kernel in the one dimensional projection; and
analyzing the results of the repeated correlations to locate a position where there is an extremum in correlation response.
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Abstract
A high speed system for locating and decoding glyphs on documents is disclosed. The system includes acquiring one or more images of a document containing a glyph. One-dimensional projections of the images are correlated against a reference function to locate the glyph in the images. The position of the glyph is refined by correlating against a kernel designed to have a maximum response when aligned over a corner of the glyph. Symbols in the glyph are decoded utilizing a kernel which generates a positive response for one symbol type and a negative response for the other.
84 Citations
21 Claims
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1. A method of locating a glyph on a document, where the glyph contains symbols positioned in a grid of rows and columns, the method comprising:
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scanning the document to acquire at least one image of at least part of the document; preparing a one-dimensional kernel function having a strong correlation response when aligned with a one-dimensional projection of a glyph; computing a one-dimensional projection over at least part of the image, where the at least part of the at least one image includes at least part of the glyph; correlating the one-dimensional projection with the kernel function, where the kernel is located at a selected position in the projection; repeating the step of correlating for a plurality of relative positions of the kernel in the one dimensional projection; and analyzing the results of the repeated correlations to locate a position where there is an extremum in correlation response. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of decoding symbols from an image of a glyph, where there are first and second symbol types in the glyph, each symbol type having a predetermined pattern, the method comprising:
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forming a kernel function, where the kernel function includes positive entries in locations corresponding to the pattern of the first symbol type and negative entries in locations corresponding to the pattern of the second symbol type; computing a correlation between the kernel function and a symbol in the glyph; and declaring the symbol to be of the first type if the result of the correlation exceeds a first predetermined value and declaring the symbol to be of the second type if the result of the correlation is less than a second predetermined value. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method of finding the location of symbols within an image incorporating a glyph with a plurality of symbols disposed in a regular array of cells therein, where the symbols include a first type and a second type, each type having a predetermined pattern with the two patterns having a region of intersection, the method comprising:
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forming a correlation kernel including a plurality of cells corresponding to the symbol cells, at least a portion of the kernel cell including non-zero entries at locations corresponding to the region of intersection of the symbol cells; and conducting a correlation of the kernel with a selected portion of the image for a plurality of selected portions of the image to search for a maximum correlation response. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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Specification