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Digital image watermark extraction method based on DCT algorithm

A technology of digital image and watermark extraction

Inactive Publication Date: 2012-07-25
SHAANXI UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The energy of the watermark signal embedded by the transform domain algorithm can be distributed to all pixels in the airspace, which is a widely used type of algorithm, but its embedding position is the entire image, which is not conducive to the invisibility of the watermark
After the traditional watermark extraction method extracts the watermark, part of the image will be lost, and it has no self-compensation function, and the image cannot be arbitrarily increased

Method used

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  • Digital image watermark extraction method based on DCT algorithm
  • Digital image watermark extraction method based on DCT algorithm
  • Digital image watermark extraction method based on DCT algorithm

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0046] Taking an image with a size of 128×128 pixels as an example to illustrate the implementation steps of this embodiment:

[0047] The first step is to read the original image and the watermarked image with a size of 128×128 pixels, and divide them into 32×32 image blocks that do not cover each other, and perform DCT domain transformation on the original image and the image to be tested respectively. Perform difference calculations to determine sequence positions:

[0048] Embedding rule: v′ i =v i (1+αw i )

[0049] Corresponding extraction rule: v′ i -v i =αv i w i

[0050] where v i , v' i are the frequency domain coefficients before and after modification, respectively, α is the stretching coefficient, w i is the i-th information bit watermark;

[0051] In the second step, the variance of the image blocks is compared, and the texture blocks are separated, so as to determine the position where the watermark is embedded in the image:

[0052] When extracting...

Embodiment 2

[0064] Taking an image with a size of 256×256 pixels as an example to illustrate the implementation steps of this embodiment:

[0065] The first step is to read the original image and the watermarked image with a size of 256×256 pixels, and divide them into 32×32 image blocks that do not cover each other. The original image and the image to be tested are respectively subjected to DCT domain transformation, and the difference calculation is performed to determine the sequence position:

[0066] Embedding rule: v' i =v i (1+αw i )

[0067] Corresponding extraction rule: v′ i -v i =αv i w i

[0068] where v i , v' i are the frequency domain coefficients before and after modification, respectively, α is the stretching coefficient, w i is the i-th information bit watermark;

[0069] In the second step, the variance of the image blocks is compared, and the texture blocks are separated, so as to determine the position where the watermark is embedded in the image:

[0070...

Embodiment 3

[0082] Taking an image with a size of 512×512 pixels as an example to illustrate the implementation steps of this embodiment:

[0083] The first step is to read the original image and the watermarked image with a size of 512×512 pixels, and divide them into 64×64 image blocks that do not cover each other. The original image and the image to be tested are respectively subjected to DCT domain transformation, and the difference calculation is performed to determine the sequence position:

[0084] Embedding rule: v' i =v i (1+αw i )

[0085] Corresponding extraction rule: v′ i -v i =αv i w i

[0086] where v i , v' i are the frequency domain coefficients before and after modification, respectively, α is the stretching coefficient, w i is the i-th information bit watermark;

[0087] In the second step, the variance of the image blocks is compared, and the texture blocks are separated, so as to determine the position where the watermark is embedded in the image:

[0088...

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Abstract

The invention discloses a DCT algorithm-based method for digital image watermark extraction, which comprises the following steps: firstly, performing the DCT domain conversion of an original image and an image to be tested respectively, performing subtraction, and determining sequence positions; secondly, comparing the variances of image blocks and sorting out texture blocks so as to determine the position at which a watermark is embedded into the image; thirdly, forming one-dimension watermark sequence according to the sequence positions; and fourthly, recombining the one-dimension watermarksequence into a two-dimension watermark and restoring the image. The method has the characteristics of an automatic compensation function and random frame increase.

Description

technical field [0001] The invention belongs to the technical field of image watermark extraction, in particular to a digital image watermark extraction method based on a DCT (discrete cosine transform) algorithm. Background technique [0002] With the progress of the times, the rapid development of network and communication technology has brought great convenience to human information exchange, and the digitization of multimedia data has promoted the access of multimedia information, making the communication and dissemination of information unprecedented. However, the problems of copyright protection and security certification of digital products have also become very serious. Traditional encryption technology and digital signature technology cannot completely solve the problem of copyright protection, and it is difficult to meet the requirements of the current era. [0003] Watermark extraction technology can extract the watermark through certain technical detection means,...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06T1/00G06T9/00
Inventor 兀旦晖赵晨飞杨萍谭歆李秦君
Owner SHAANXI UNIV OF SCI & TECH
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