Half-tone dot eliminating method and its system

A technology of halftone dots and connecting patterns, which is applied in the field of halftone dot elimination and its systems, and can solve the problem of impossible character recognition.

Inactive Publication Date: 2003-03-19
FUJITSU LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Otherwise, character recognition is impossible, which creates problems

Method used

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  • Half-tone dot eliminating method and its system
  • Half-tone dot eliminating method and its system
  • Half-tone dot eliminating method and its system

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Embodiment Construction

[0021] According to a preferred embodiment of the present invention, a halftone dot grid area is detected based on pattern density in a document, and halftone dots and shadows due to overlapping of halftone dots with characters are eliminated. After the halftone dotted area is extracted, the vertical / horizontal size mean and standard deviation of the pattern in the halftone dotted area are calculated respectively. Since the number of dot patterns in the halftone dot grid area is very large compared to the number of character patterns, each mean value and standard deviation value are affected by the size of the dot pattern and the dispersion of the size. If the standard deviation is small, it is determined that the size dispersion of the dot pattern is small and the size is almost constant, and the value obtained by adding a small value to the average value is used to distinguish characters from the dot pattern Pattern threshold. If the standard deviation is large, it is deter...

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Abstract

After an original image, including half-tone dot meshed characters is inputted and a prescribed process is applied to the original image, black pixel connected patterns are extracted from a target process area. If the density of the extracted pattern exceeds a prescribed density, it is judged that the pattern is half-tone dot meshed and both the respective average values and standard deviations of the vertical / horizontal sizes of the connected pattern are calculated. Then, respective threshold values are calculated based on both the respective average values and standard deviations, and half-tone dots are eliminated. Then, a pattern, the outline of which is long compared with an included black pixel, out of the remaining connection patterns is eliminated as an unnecessary pattern. Lastly, projections attached to a character are deleted and character extraction is terminated.

Description

technical field [0001] The present invention relates to a half-tone dot removal method and system thereof for accurately extracting characters from a half-tone dot meshed image in a character recognition apparatus and the like. Background technique [0002] Although character recognition of documents will be described below, the following techniques generally relate to techniques for extracting characters from halftone dot-screen images in a broader sense, ie, not only in documents but also in drawings. The present invention is not limited to the technique of extracting halftone dot screen characters. [0003] Recently, with the spread of input devices such as scanners, opportunities to process images have increased, and therefore, demand for OCR (Optical Character Recognition), a character recognition device (software), is increasing. [0004] A conventional halftone dot removal method is described below. [0005] traditional method 1 [0006] In extracting characters f...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T5/00G06T7/40G06V30/10H04N1/38H04N1/409
CPCG06T5/20G06K2209/01G06T5/002H04N1/409G06K9/346G06V30/10G06V30/155G06V10/36
Inventor 小原敦子藤本克仁直井聪
Owner FUJITSU LTD
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