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Method for extracting watermark image

A watermark image and extraction method technology, applied in the field of image processing, can solve the problems of reducing imperceptibility, difficult blind extraction, and high embedding difficulty

Active Publication Date: 2013-01-16
JIANGSU UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the limitation of information hiding capacity, using grayscale image as image watermark for embedding is not only difficult to embed, but also difficult to achieve blind extraction. While improving the robustness of embedded watermark, it also reduces its imperceptibility. not much research

Method used

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  • Method for extracting watermark image
  • Method for extracting watermark image
  • Method for extracting watermark image

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Experimental program
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Embodiment 1）

[0050] See Figure 1-3 , the embedding object of the watermark image in this embodiment is a matrix as The original carrier image (M=N=512, that is, the image whose length and width are 512 pixels), its format is an uncompressed 8-bit high-precision grayscale bitmap (bmp or tiff), and JPG format can also be selected image. The grayscale watermark image generally selects a trademark or copyright mark, and the total number of pixels n is required to be smaller than that of the carrier image (n<M / 8*N / 8). In the embodiment, a grayscale watermark with a pixel size of 40×49 is selected.

[0051] The steps of determining the embedding position of the carrier image and embedding the grayscale watermark information are as follows:

[0052] (1) Preprocessing of watermarked images. In order to ensure the security of the watermark, the watermark image is scrambled by some algorithms (such as chaotic sequence scrambling method, etc.), and the scrambled image is recorded as W, and the i...

Embodiment 2）

[0071] The recovery and authentication steps of the grayscale watermarked image are as follows:

[0072] (a) For the original carrier image matrix is , the watermarked image to be checked is , respectively divided into a corresponding number of 8×8 image blocks that do not cover each other, and perform DCT transformation on each image block, and extract the corresponding low-frequency and high-frequency data from each 8×8 image block according to the 8×8 template, and Construct a 3×3 matrix for the low-frequency and high-frequency data in each 8×8 image block in the original carrier image with a 6x6 matrix , for the low-frequency and high-frequency data in each 8×8 image block of the watermarked image, respectively form a matrix of 3×3 matrix with a 6x6 matrix , for the matrix , Separate singular value decomposition: , ;

[0073] (b) Solve the change value of watermark information in each 8×8 image block , , m is the total number of blocks that the origi...

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Abstract

The invention relates to a method for extracting a grayscale watermark image. The method is suitable for solving the problem of conflict between the transparency and robustness of a watermarking algorithm. The method comprises the following steps of: dividing an original carrier image and a watermark image to be detected into corresponding numbers of image blocks without coverage, performing discrete cosine transformation (DCT) on each image block, finding a low-frequency data matrix A from each image block according to a template, performing singular value decomposition on each matrix A, separating information from singular values, and recovering the grayscale watermark image on the basis of adaptive embedding principle according to the energy ratio of the image blocks.

Description

[0001] This application is a divisional application, the application number of the original application: 201110139206.9, the application date: 2011-5-26, and the name of the invention: the embedding and extraction method of watermark image. technical field [0002] The invention relates to the technical field of image processing, in particular to a watermark image extraction method. Background technique [0003] With the rapid development of digital multimedia technology and Internet technology, the security of multimedia products has become a very important and challenging research topic. Digital watermarking technology is a potentially effective method to realize the copyright protection of digital products. It has become a research hotspot in the field of information security and an important branch of information hiding research. It is against this background that digital watermarking comes into being. It has become a frontier and hot direction of current academic resear...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T1/00
Inventor 王海峰章怡
Owner JIANGSU UNIV OF TECH