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Printed document evidence obtaining method for detecting authenticity of document by using half-tone information

A technology for printing documents and information detection, applied in image communication, electrical components, etc.

Inactive Publication Date: 2012-07-04
DALIAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

If it is printed by document editing software, it is considered that there is no forgery of cutting and combining for secondary printing; if it is printed in the form of an image, it is considered that there is a high possibility of forgery of cutting and combining for secondary printing

Method used

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  • Printed document evidence obtaining method for detecting authenticity of document by using half-tone information
  • Printed document evidence obtaining method for detecting authenticity of document by using half-tone information
  • Printed document evidence obtaining method for detecting authenticity of document by using half-tone information

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Experimental program
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Embodiment Construction

[0044] The specific embodiments of the present invention will be described in detail below in conjunction with the technical solutions and accompanying drawings.

[0045] In the experiment, it is necessary to detect whether the character image of the printed document contains halftone information. First, a character document image containing halftone information must be produced. The upper half of the document is the image of the printed and scanned character "e", and the lower half Part of it is the normal character "e". Print and scan the document to obtain the image of the document to be detected. The upper half of the image contains halftone, and the lower half does not contain halftone, so as to facilitate the comparison of detection results. The scanning accuracy is used in the experiment 600dpi. Figure 7 (a) is a part of the document to be detected. The upper three lines contain halftones, and the lower three lines do not contain halftones. The detection results are as...

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Abstract

The invention discloses a printed document evidence obtaining method for detecting authenticity of a document by using half-tone information, which belongs to the technical field of signal and information processing. The method is characterized by comprising the following steps of: after the document is printed twice, introducing sine noise into the document so that the printed document has half tone and generates four peak values in four quadrants of a frequency spectrum thereof; and obtaining an image block of each character through character partition, solving and normalizing a logarithm amplitude spectrum of the image block, designing a band-pass filter function with a peak value in four quadrants, judging whether the half tone exists by calculating the correlation between the normalized logarithm amplitude spectrum and the band-pass filter function, and further judging whether the printed document is subjected to secondary printing falsification. The method has the advantage of automatically judging whether each character image of the printed document has half tone to identify whether the document is subjected to the secondary printing falsification.

Description

technical field [0001] The invention belongs to the technical field of signal and information processing, relates to a printing document evidence collection method for detecting document authenticity, in particular to a printing document evidence collection method for detecting document authenticity by using halftone information. Background technique [0002] There are usually two ways to forge documents: the forgery of adding text through direct secondary printing; printing after editing operations such as adding, deleting, and modifying text on scanned documents, which is called cutting and combining secondary printing. [0003] Wang Yue and others pointed out in the article "A New Exploration of the Inspection Method of Adding Printed Documents" that the former inevitably causes forgery defects visible to the naked eye, such as the difference in the lateral inclination of the line writing, the difference in the line spacing, and the difference in the left and right page ma...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04N1/40H04N1/405
Inventor 孔祥维吴玉宝
Owner DALIAN UNIV OF TECH
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