IMAGE READING APPARATUS
First Claim
1. A method for processing image data read from a book document placed on a platen, the method comprising:
- determining a target pixel of the image data as a background pixel when a difference between the target pixel and a neighboring pixel is less than a threshold (step 1);
performing a preliminary luminance correction calculation using a same correction value candidate for a luminance value of a background pixel positioned on a line parallel to a binding portion of the book document (step 2);
integrating an absolute value of a difference between a value obtained by the preliminary luminance correction calculation and a luminance value of a neighboring background pixel positioned at one side of the line with respect to background pixels on the line, and selecting a correction value candidate that minimizes the integrated value among a plurality of correction value candidates as a correction value of the background pixel on the line (step 3);
calculating a cumulative luminance correction value for each line by successively performing a luminance correction calculation in neighboring order of the line based on the selected correction value (step 4);
extracting a shadow region of at least one of a shadow of a binding portion or a shadow of a front edge portion involved in the image data based on the cumulative luminance correction value (step 5); and
performing a luminance correction on the shadow region based on the cumulative luminance correction value (step 6).
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Accused Products
Abstract
A method is provided for processing image data read from a book document placed on a platen of an image reading apparatus. The method includes determining a background pixel of the image data based on a luminance difference or a color difference between neighboring pixel arrays, identifying a shadow region based on a luminance change between the neighboring background pixel arrays, discriminatively detecting a shadow of a binding portion and a shadow of a front edge in a document region with reference to a changing direction of shadow luminance, and performing a luminance correction on the shadow region according to characteristics of the shadows.
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Citations
17 Claims
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1. A method for processing image data read from a book document placed on a platen, the method comprising:
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determining a target pixel of the image data as a background pixel when a difference between the target pixel and a neighboring pixel is less than a threshold (step 1); performing a preliminary luminance correction calculation using a same correction value candidate for a luminance value of a background pixel positioned on a line parallel to a binding portion of the book document (step 2); integrating an absolute value of a difference between a value obtained by the preliminary luminance correction calculation and a luminance value of a neighboring background pixel positioned at one side of the line with respect to background pixels on the line, and selecting a correction value candidate that minimizes the integrated value among a plurality of correction value candidates as a correction value of the background pixel on the line (step 3); calculating a cumulative luminance correction value for each line by successively performing a luminance correction calculation in neighboring order of the line based on the selected correction value (step 4); extracting a shadow region of at least one of a shadow of a binding portion or a shadow of a front edge portion involved in the image data based on the cumulative luminance correction value (step 5); and performing a luminance correction on the shadow region based on the cumulative luminance correction value (step 6). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A computer-readable medium storing instructions which, when executed by an apparatus, causes the apparatus to perform operations comprising:
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obtaining image data generated by scanning and reading a book document placed on a platen of an image scanner; determining a target pixel of the image data as a background pixel when a difference between the target pixel and a neighboring pixel is less than a threshold; performing a preliminary luminance correction calculation using a correction value candidate for a luminance value of a background pixel positioned on a line parallel to a binding portion of the book document; selecting a correction value candidate from a plurality of correction value candidates as a correction value of the background pixel on the line; calculating a cumulative luminance correction value for each line by successively performing a luminance correction calculation in neighboring order of the line based on the selected correction value; extracting a shadow region of at least one of a shadow of a binding portion or a shadow of a front edge portion included in the image data based on the cumulative luminance correction value; and performing a luminance correction on the shadow region based on the cumulative luminance correction value. - View Dependent Claims (17)
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Specification