Method for classifying pixel blocks of JPEG images and image falsification detecting and falsified area positioning methods based on same

A classification method and a technology of pixel blocks, which are applied in character and pattern recognition, instruments, computer parts, etc., can solve the problems of detection and positioning of tampered areas, etc.

Inactive Publication Date: 2012-06-27
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] But at present, using the principle and method of this classifier disclosed in the literature, it is only possible to make a judgment on the compression history of the entire image of the JPEG image, and it has not yet been able to detect and locate the tampered area of ​​a given JPEG image.

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  • Method for classifying pixel blocks of JPEG images and image falsification detecting and falsified area positioning methods based on same
  • Method for classifying pixel blocks of JPEG images and image falsification detecting and falsified area positioning methods based on same
  • Method for classifying pixel blocks of JPEG images and image falsification detecting and falsified area positioning methods based on same

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Embodiment 1

[0028] Assuming that a JPEG image is tampered and saved as JPEG format again, the tampered area and the non-tampered area generally have different compression histories. For copy-paste tampering and the insertion area is from an uncompressed image (referred to as "JPEG+uncompressed") and JPEG image retouched tampering (referred to as "JPEG+retouched") two tampering methods, the tampered area has undergone JPEG single compression, while the untampered area Experienced JPEG block-matching double compression; for copy-paste tampering and the insertion area comes from a JPEG image (abbreviation, "JPEG+JPEG") tampering method, the probability of the tampered area undergoing JPEG block-matching double compression is only 1 / 64, and the probability of experiencing JPEG block is not There is a 63 / 64 chance of matching double compression, and the untampered region has undergone JPEG block matching double compression. Our experiments show that the probability distributions of the first d...

Embodiment 2

[0030] A method for classifying pixel blocks of JPEG images, comprising the following steps:

[0031] (1) Select a sufficient number of uncompressed images to perform JPEG single compression and JPEG block matching double compression respectively, select the first 20 AC coefficient bands of the image, and calculate the first digit of the AC coefficient in each AC coefficient band (i.e. 1 to 9 ) probability distribution, thereby obtaining a feature vector of 20×9=180 dimensions, and then training a single compression / double compression classifier for two classifications;

[0032] (2) Select a sub-image on the image to be detected, the method is: divide the JPEG image to be detected into continuous non-overlapping 8×8 pixel blocks, such as image 3 As shown, each small square in the figure is an 8×8 pixel block, image 3(a) is the sub-image selection method under normal circumstances, that is, select 3×3 (that is, the scheme where the value of n in (2n+1)×(2n+1) is 1) with a ce...

Embodiment 3

[0037] After adopting the method of embodiment 2 to classify all the pixel blocks in the image to be detected, in order to eliminate the influence of noise in the detection results and the resulting misjudgment, when more than M classification results are single-compressed pixel blocks form When the connected regions are connected, the image to be detected is judged as a tampered image, where M is set to 25.

[0038] Further, in order to locate the tampered area of ​​the JPEG image, after all the pixel blocks in the image to be detected are classified by the method of Embodiment 2, all M or more (M is set to 25) classification results are found as Connected areas formed by single compressed pixel blocks, mark these areas as "1", which means tampered areas, and mark other areas as "0", that is, untampered areas.

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Abstract

The invention provides a method for classifying pixel blocks of JPEG images and image falsification detecting and falsified area positioning methods based on the same. The method comprises the following steps of: dividing to-be-detected JPEG images into continuous and non-overlapped 8*8 pixel blocks; taking one pixel block as the center and selecting a square area combined by (2n+1)*(2n+1) pixel blocks as a sub-image; utilizing a first number distribution probability feature of AC coefficients in the front i AC coefficient regions of the sub-image to divide the central pixel block into singlecompression or double compression; and confirming a classifying result as the double compression and a connected region with an area more than M 8*8 pixel blocks as a falsified area. According to themethod provided by the invention, the falsified area can be accurately detected and positioned; the falsified areas of three different falsifying technologies can be detected according to the method;the method is wide in application scope; the method is an automatic blind detecting method for JPEG falsified images and does not require any priori knowledge; and the detection coverage rate is higher and the error detection rate is low.

Description

technical field [0001] The invention relates to a method for judging whether a digital image has been tampered with, in particular to a method for judging whether a JPEG image has been tampered with and locating the tampered area. Background technique [0002] With the emergence of increasingly complex image editing software, people can easily tamper with digital images without leaving obvious traces. Therefore, the technical requirements for authenticity identification of digital images and detection of tampered areas are increasing, but at present A variety of detection methods for digital image authenticity identification and tampered areas still have shortcomings such as limited application and high false detection rate. [0003] In the document "Detecting doubly compressed JPEG images by using mode based first digit features" (IEEE International Workshop on Multimedia Signal Processing, pp.730-735, 2008.), it is disclosed by calculating the first digit distribution of t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06K9/62G06K9/46
Inventor 赵于前廖苗
Owner CENT SOUTH UNIV
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