Detection method for secondary compression of JPEG image

A technology of secondary compression and detection methods, which is applied in image coding, image data processing, instruments, etc., and can solve problems such as inapplicability, inaccurate estimation, and large amount of calculation.

Inactive Publication Date: 2011-03-23
BEIJING UNIV OF POSTS & TELECOMM
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Problems solved by technology

[0004] The disadvantage of the above method is that the amount of calculation is large, the algorithm is complex, and in some cases, such as cropping the detection image wil

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  • Detection method for secondary compression of JPEG image
  • Detection method for secondary compression of JPEG image
  • Detection method for secondary compression of JPEG image

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Embodiment Construction

[0045] figure 1 Is the general flow chart of the detection process.

[0046] (1) Select the directory to be detected, then read the JPEG images to be detected sequentially from it, judge the image format, skip if it is not in JPEG format, and continue to read the next image.

[0047] (2) Fit the distribution function of the AC coefficient of a JPEG compression by the AC coefficient of the JPEG image to be detected, and obtain an estimate of the distribution function of the AC coefficient of a JPEG compression, denoted as F 1 (x), where x represents the value of the AC coefficient (the value range of x is an integer from -128 to 128).

[0048] (3) Normalize the histogram of the AC coefficient of the JPEG image to be detected, with f 2 (x) represents the normalized histogram of the AC coefficient of the image to be detected. The so-called normalization is to convert the frequency of occurrence corresponding to x to the percentage of the frequency of occurrence, and the normali...

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Abstract

The invention provides a detection method for secondary compression of a JPEG image. By using the characteristic that an AC coefficient histogram in a DCT coefficient of primary JPEG compression accords with Laplace distribution, a Laplace distribution function of the AC coefficient of the primary JPEG compression of an image to be detected is estimated in a fit mode according to the AC coefficient distribution of the JPEG image to be detected; the statistic is detected through a difference structure of normalized histogram distribution of the fit distribution function and an actual AC coefficient; and whether the JPEG image is subjected to the secondary compression is judged by using SVM classification. The method has high detection accuracy and wide applicability.

Description

technical field [0001] The invention relates to the field of image tampering detection, and specifically provides a new method for detecting secondary compression of JPEG images. Background technique [0002] JPEG is the abbreviation of joint photographic experts group. The JPEG compression standard provides a compression method suitable for various continuous tone images. The original image type can be independent of image size, content, statistical characteristics, pixel shape and The limitation of color space allows files to be compressed with different compression ratios to obtain better image quality, and can reduce image transmission time, so it is widely used in the Internet and other still image fields. In the past ten years, due to the widespread use of image editing software, the authenticity of digital images has become more and more important. [0003] The second JPEG compression refers to the use of different quality factors Q 1 and Q 2 Do JPEG compression tw...

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Application Information

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IPC IPC(8): G06T9/00
Inventor 马荣敏张茹陈铭钮心忻杨义先
Owner BEIJING UNIV OF POSTS & TELECOMM
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