Preprocessing for information pattern analysis
First Claim
1. A method of normalizing brightness in an image, comprising:
- receiving an image made up of areas, each area having an original brightness value;
dividing the image up into blocks of areas;
determining an estimated brightness of each block;
determining an brightness distribution value for each area by fitting the estimated brightness determined for each block surrounding the area using bilinear interpolation and extrapolation;
normalizing a brightness value for each area by dividing an original brightness value for the area by the brightness distribution value determined for the area to produce a normalized brightness value; and
creating a new image using the normalized brightness value for each area.
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Accused Products
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.
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Citations
17 Claims
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1. A method of normalizing brightness in an image, comprising:
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receiving an image made up of areas, each area having an original brightness value;
dividing the image up into blocks of areas;
determining an estimated brightness of each block;
determining an brightness distribution value for each area by fitting the estimated brightness determined for each block surrounding the area using bilinear interpolation and extrapolation;
normalizing a brightness value for each area by dividing an original brightness value for the area by the brightness distribution value determined for the area to produce a normalized brightness value; and
creating a new image using the normalized brightness value for each area. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of identifying an information pattern in an image of a document, 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. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A pattern determination tool, comprising:
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a high-contrast region determination module that identifies high-contrast regions in an image;
a pattern brightness threshold determination module that determines a pattern brightness value threshold to identify areas of the image that represent an information pattern; and
a pattern identification module that identifies an area as a pattern area if a brightness value of the area is below the pattern brightness value threshold. - View Dependent Claims (14, 15, 16, 17)
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Specification