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Method and device for imbedding and extracting watermark in digital image

A digital image, embedding watermark technology, applied in the field of information hiding and image steganography, can solve problems such as hiding, and achieve the effect of resisting steganalysis and good steganalysis

Active Publication Date: 2008-08-20
PEKING UNIV +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the regularity of the histogram of the hidden image, it is easy to detect the secret information hidden in the image by various steganalysis methods.

Method used

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  • Method and device for imbedding and extracting watermark in digital image
  • Method and device for imbedding and extracting watermark in digital image
  • Method and device for imbedding and extracting watermark in digital image

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0111] Embodiment 1, the method for embedding a watermark in a digital image:

[0112] 1. Obtain the grayscale image “Man” as shown in FIG. 2A , the size of which is 512×512.

[0113] 2. Obtain the watermark bit stream string composed of 0 and 1 whose length is 512×512-1=262143:

[0114] W=(W 1 , W 2 ,...,W 262143 ).

[0115] 3. Sort all the pixels of the grayscale image from left to right and then from top to bottom, and then divide the first 262143 pixels into 262143÷3=87381 groups according to the arrangement order, and each group contains three pixels. Assume that the pixel values ​​of the three pixels contained in the i-th pixel group are X i，1 、X i，2 and x i，3 , thus obtaining the pixel value signal sequence,

[0116] x 1 , X 2 ,...,X 87381

[0117] The pixel value signal labeled i is X i =(X i，1 , X i，2 , X i，3 ), i ∈ {1, 2, ..., 87381}.

[0118] 4. Divide the watermark bit stream string W into 262143÷3=87381 groups, each group contains three bit stream...

Embodiment 2

[0221] Embodiment 2, the method for extracting watermark in digital image:

[0222] 1. Obtain a grayscale image embedded with a watermark as shown in FIG. 2B , the size of which is 512×512.

[0223] 2. Group all or part of the pixels of the grayscale image in the same way as embedding the watermark, and a total of 87381 groups are obtained, and each group contains three pixels. Assume that the pixel values ​​of the three pixels contained in the i-th pixel group are Y in turn i，1 , Y i，2 and Y i，3 , where i ∈ {1, 2, ..., 87381}.

[0224] 3. Calculate the pixel value signal,

[0225] Y i =(Y i，1 , Y i，2 , Y i，3 )

[0226] with a digital signal,

[0227] V=(V 1 , V 2 , V 3 )=(1, 2, 3) and determine the watermark signal according to the calculated inner product. Specifically, first calculate,

[0228] H=Y i，1 ·V 1 +Y i，2 ·V 2 +Y i，3 ·V 3 =Y i，1 +2Y i，2 +3Y i，3 ;

[0229] Then calculate H divided by 2 3 Get the remainder, i.e. find M∈{0,1,...,7} such that,...

Embodiment 3

[0267] Use the method for embedding watermark described in the present invention and select the digital signal V=(1,2,4,8,15) that satisfies the requirements, for the gray levels shown in Fig. 2A and Fig. 3, Fig. 4, Fig. 5 and Fig. 6 The image is respectively embedded with a watermark bit stream string composed of 0 and 1 with a length of 512×512-4=262140. This process makes the average watermark embedding amount of each pixel of the image be (512×512-4) / (512×512 ) ≈ 1, the average change of the pixel value of each point in the image is 0.3343, 0.3252, 0.3259, 0.3251 and 0.3250, which are consistent with the theoretical value of 0.325. Note that the selection of the vector S representing the modular residual class corresponding to the digital signal V=(1,2,4,8,15) satisfying the requirements is as follows:

[0268] M

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Abstract

The present invention provides a method and device of embedding watermark in the digital image, including: full or part pixel of digital image to be embedded is grouped, the number of the pixel of each group is more than three; the watermark bit stream string to be embedded is grouped, each group contains a watermark signal, the grouping number of the watermark bit stream string is identical to the grouping number of the digital image pixel; the pixel changing signal of the pixel signal is calculated according to each pixel signal and corresponding watermark signal and a digital signal; the grouping pixel of the corresponding digital image pixel is changed according to the pixel changing signal, realizing watermark embedded. The invention also provides a method and device of extracting watermark. The embodiment of the invention makes the average changing amount of each pixel less under the condition that the each pixel is changed more than 1 and keeps a certain information conceal capacity, having more resist steganalysis.

Description

technical field [0001] The invention relates to the technical fields of information hiding and image steganography, in particular to a method and device for embedding and extracting watermarks in digital images. Background technique [0002] Information hiding is a new research hotspot in the field of information security. Information hiding includes secret-related data communication in an open network environment, intellectual property protection of digital products, authenticity identification of important documents and digital signatures, and post-disclosure of confidential documents. The source tracking of news provides reliable information security guarantee. Digital watermarking and image steganography are two branches of information hiding technology. [0003] Existing technology 1: It is proposed to insert secret information into the lowest bit of the pixel value of the original image pixel by pixel, which can ensure that the visual effect of the image is maintained...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T1/00
CPCG06T1/0021G06T2201/0051G06T2201/0061H04N1/32203H04N5/913H04N2005/91335
Inventor 李晓龙杨斌程道放亓文法
Owner PEKING UNIV
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