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Embedding method and extracting method of reversible watermarks

A technology of watermarking and embedding watermark, applied in the fields of information hiding and digital watermarking

Inactive Publication Date: 2011-05-04
PEKING UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0020] The purpose of the present invention is to provide a method for embedding a reversible watermark in a digital image and its extraction method, which can ensure better visual effects and solve the problem of freely embedding watermarks according to the embedding rate

Method used

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  • Embedding method and extracting method of reversible watermarks
  • Embedding method and extracting method of reversible watermarks
  • Embedding method and extracting method of reversible watermarks

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0087] Example 1: We assume that there is a pixel value around a pixel as follows:

[0088] 162

163

165

170

[0089] For the pixel point in the upper left corner (x=162), using the MED prediction method, the predicted value can be obtained as x'=163, and the predicted error e=x-x'=162-163=-1 can be calculated. Forecast errors belong to the inner region, where information can be embedded. Suppose the binary bit to be embedded is b=1, then e'=e-b=-1-1=-2, x w =x'+e'=163-2=161, that is, after embedding:

[0090] 161

163

165

170

[0091] If the binary to be embedded is 0, then, e'=-1, x w =x'+e'=163-1=162, that is, after embedding:

[0092] 161

Embodiment 2

[0094] We assume that there are pixel values ​​around a pixel as follows:

[0095] 162

162

162

162

[0096] For the pixel point in the upper left corner (x=162), using the MED prediction method, the predicted value can be obtained as x'=162, and the prediction error e=x-x'=162-162=0 is calculated, and Therefore, no data information is embedded and the prediction error remains unchanged. The pixel value after embedding is:

[0097] 162

Embodiment 3

[0099] We assume that there are pixel values ​​around a pixel as follows:

[0100] 162

169

169

180

[0101] For the pixel point in the upper left corner (x=162), using the MED prediction method, the predicted value can be obtained as x'=169, and the prediction error e=x-x'=162-169=-7 is calculated, and Therefore, no data information is embedded, and the prediction error needs to be moved to the left, that is, e′=e-1=-7-1=-8, x w =x'+e'=169-8=161, that is, after embedding:

[0102] 161

169

169

180

[0103] The above method uses MED to predict the pixel value. In fact, it can be seen from the analysis that the present invention has nothing to do with the prediction method. In other words, any prediction method can be combined with the technology of the present invention. In general, the more accurate the prediction method, the better the embedding.

[0104] Figure 5 An experimental comparison of the pr...

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Abstract

The invention discloses an embedding method and an extracting method of reversible watermarks, belonging to the technical field of digital watermarks. The embedding method comprises the following steps of: sequentially reading the pixel values of digital images, and establishing a position sign sequence; compressing the position sign sequence, and regulating a pixel with the pixel value of 0 or 255; calculating forecast error sequences of the digital images, and selecting internal areas and parameters T which are needed in the embedding process; and embedding the reversible watermarks according to the selected parameters. The extracting method comprises the following steps of: sequentially reading the pixel values of the digital images, and extracting various kinds of auxiliary information; uncompressing the compressed position sign sequence to obtain the uncompressed position sign sequence; carrying out inverse solution referring to the embedding parameters so as to obtain embedding information; regulating the pixel values according to the position sign sequence; and finally, sequentially substituting the sequences for least significant bits of the pixel values, wherein carrier images can be completely recovered at the time. The invention can successfully realize the embedding and the extraction of the reversible watermarks on gray level images and the recovery of original images.

Description

technical field [0001] The invention belongs to the technical field of information hiding and digital watermarking, and in particular relates to a method for embedding a reversible watermark in a digital image and an extraction method thereof. Background technique [0002] Information Hiding is a new research hotspot in the field of information security. In the past ten years, the research in this direction has attracted more and more people's attention, and the research team has expanded rapidly. has been widely applied. It provides a reliable information security guarantee for confidential data communication in an open network environment, intellectual property protection of digital products, authenticity verification of important documents and digital signatures, and source tracking of confidential documents after leaks. [0003] Digital watermarking (Digital Watermarking) and image steganography (Steganography) are two branches of information hiding technology. These t...

Claims

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Application Information

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IPC IPC(8): G06T1/00
Inventor 李晓龙王超亓文法杨斌
Owner PEKING UNIV
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