Method and apparatus for identification of documents, and computer product
First Claim
1. A document identification apparatus for discriminating various documents by comparing a feature quantity of image data of an input image of a document with a feature quantity of image data of at least one reference image stored beforehand, the document identification apparatus comprising:
- a calculation unit which calculates a black pixel ratio, which black pixel ratio is a ratio of black pixels existing in a predetermined number of continuous pixels in horizontal or vertical direction from a specific pixel in the image data of the input image or the reference image; and
an extraction unit which divides the image data into a plurality of blocks, and separately adds the black pixel ratios corresponding to every pixel located in every block to extract a feature quantity of the image data.
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Abstract
In the document identification apparatus, a ruled line feature extraction section determines a black pixel ratio of a document to be identified, and adds the black pixel ratio for each block to extract a ruled line feature. A ruled line feature verification section verifies the ruled line feature with a ruled line feature already registered in a ruled line feature dictionary to thereby identify the document. If identification is not possible with this procedure, a details judgment section verifies the image data in a specific area with the image data (characters or the like) registered in a specific area dictionary.
22 Citations
12 Claims
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1. A document identification apparatus for discriminating various documents by comparing a feature quantity of image data of an input image of a document with a feature quantity of image data of at least one reference image stored beforehand, the document identification apparatus comprising:
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a calculation unit which calculates a black pixel ratio, which black pixel ratio is a ratio of black pixels existing in a predetermined number of continuous pixels in horizontal or vertical direction from a specific pixel in the image data of the input image or the reference image; and
an extraction unit which divides the image data into a plurality of blocks, and separately adds the black pixel ratios corresponding to every pixel located in every block to extract a feature quantity of the image data. - View Dependent Claims (2, 3)
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4. A document identification method of discriminating various documents by comparing a feature quantity of image data of an input image of a document with a feature quantity of image data of at least one reference image stored beforehand, the document identification method comprising:
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a calculation step of calculating a black pixel ratio, which black pixel ratio is a ratio of black pixels existing in a predetermined number of continuous pixels in horizontal or vertical direction from a specific pixel in the image data of the input image or the reference image; and
an extraction step of dividing the image data into a plurality of blocks, and separately adding the black pixel ratios corresponding to every pixel located in every block to extract a feature quantity of the image data. - View Dependent Claims (5, 6)
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7. A computer readable recording medium which stores a computer program which contains instructions which when executed on a computer realizes a document identification method of discriminating various documents by comparing a feature quantity of image data of an input image of a document with a feature quantity of image data of at least one reference image stored beforehand, the document identification method comprising:
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a calculation step of calculating a black pixel ratio, which black pixel ratio is a ratio of black pixels existing in a predetermined number of continuous pixels in horizontal or vertical direction from a specific pixel in the image data of the input image or the reference image; and
an extraction step of dividing the image data into a plurality of blocks, and separately adding the black pixel ratios corresponding to every pixel located in every block to extract a feature quantity of the image data. - View Dependent Claims (8, 9)
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10. A computer program which contains instructions which when executed on a computer realizes a document identification method of discriminating various documents by comparing a feature quantity of image data of an input image of a document with a feature quantity of image data of at least one reference image stored beforehand, the document identification method comprising:
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a calculation step of calculating a black pixel ratio, which black pixel ratio is a ratio of black pixels existing in a predetermined number of continuous pixels in horizontal or vertical direction from a specific pixel in the image data of the input image or the reference image; and
an extraction step of dividing the image data into a plurality of blocks, and separately adding the black pixel ratios corresponding to every pixel located in every block to extract a feature quantity of the image data. - View Dependent Claims (11, 12)
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Specification