Preprocessing for information pattern analysis
First Claim
1. A method performed by a computing device having a memory and a processor for identifying an information pattern containing embedded position information in an image of a document, the method comprising:
- identifying high-contrast regions in an image of a document;
obtaining a first threshold brightness value for distinguishing areas of the image that represent content;
analyzing each area in the image to determine if a brightness value for the area is below the first threshold;
designating areas in the high-contrast regions having a brightness value below the first threshold as areas representing content so as to identify content areas and non-content areas;
obtaining a second threshold brightness value for distinguishing areas of the image that represent an information pattern;
analyzing each non-content area in the image to determine if a brightness value for the area is below the second threshold; and
designating non-content areas having a brightness value below the second threshold as pattern areas representing the information patternwherein the information pattern contains embedded position information and is used to determine the position of the image relative to the document andwherein the identifying, analyzing, and designating are performed by the processor executing instructions stored in the memory.
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Abstract
Pre-processing techniques for processing an image to improve the distinctiveness of an information pattern captured in the image before the information pattern is analyzed in a decoding process. The brightness of an image first is normalized by dividing the image into blocks of areas, such as pixels. A brightness distribution value then is determined for each area of the image by fitting the brightness of its surrounding blocks using bilinear interpolation and extrapolation, and a normalized brightness value for each area can then be obtained by dividing the original brightness value by the brightness distribution value. Next, masks are created to distinguish the information pattern from content captured in the image. The masks may be generated based upon contrast differences between the brightness of pixels representing the information pattern, the brightness of pixels representing content, and the brightness of pixels representing the background of the writing medium.
319 Citations
12 Claims
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1. A method performed by a computing device having a memory and a processor for identifying an information pattern containing embedded position information in an image of a document, the method comprising:
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identifying high-contrast regions in an image of a document; obtaining a first threshold brightness value for distinguishing areas of the image that represent content; analyzing each area in the image to determine if a brightness value for the area is below the first threshold; designating areas in the high-contrast regions having a brightness value below the first threshold as areas representing content so as to identify content areas and non-content areas; obtaining a second threshold brightness value for distinguishing areas of the image that represent an information pattern; analyzing each non-content area in the image to determine if a brightness value for the area is below the second threshold; and designating non-content areas having a brightness value below the second threshold as pattern areas representing the information pattern wherein the information pattern contains embedded position information and is used to determine the position of the image relative to the document and wherein the identifying, analyzing, and designating are performed by the processor executing instructions stored in the memory. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A system, having a memory and a processor, comprising:
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a module that identifies high-contrast regions in an image of a document; a module that obtains a first threshold brightness value for distinguishing areas of the image that represent content; a module that analyzes each area in the image to determine if a brightness value for the area is below the first threshold; a module that designates areas in the high-contrast regions having a brightness value below the first threshold as areas representing content so as to identify content areas and non-content areas; a module that obtains a second threshold brightness value for distinguishing areas of the image that represent an information pattern; a module that analyzes each non-content area in the image to determine if a brightness value for the area is below the second threshold; and a module that designates non-content areas having a brightness value below the second threshold as pattern areas representing the information pattern wherein at least one of the modules comprises computer-executable instructions stored in the memory for execution by the computer. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification