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Embedding and extraction method of visible watermark carrying hidden information and system thereof

A technology of hiding information and watermark embedding, which is applied in the fields of instruments, computing, image data processing, etc., can solve the problems of large amount of coded information, low ability of watermark to carry coded information, and watermark without intuitive meaning, etc., to achieve strong readability , improve the correctness and robustness, and the effect of strong robustness

Inactive Publication Date: 2013-12-25
PEKING UNIV +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] 2) The watermark has no intuitive meaning
[0005] Generally speaking, the first type of watermark can be used to display obvious marks to the outside world, such as unit and company logos, etc., but the ability of watermarks to carry encoded information is low
The second type of watermark carries a large amount of encoded information, but is weak in visually expressing physical meaning
Simply displaying the company's name and logo in a semi-transparent pattern cannot meet this requirement, especially on paper materials, using a semi-transparent watermark to simultaneously represent the company name or logo can carry a large amount of coded information , there is still a lack of effective means at present, and there is also a lack of effective methods for extracting the encoded information carried by this watermark in the later stage

Method used

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  • Embedding and extraction method of visible watermark carrying hidden information and system thereof
  • Embedding and extraction method of visible watermark carrying hidden information and system thereof
  • Embedding and extraction method of visible watermark carrying hidden information and system thereof

Examples

Experimental program
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Embodiment 1

[0060] In this embodiment, a translucent watermark is embedded in a Word document, and there is only one watermark graphic element, that is, K=1. The watermark graphic element is a logo pattern of a certain company, and the hidden information that needs to be carried in the watermark is the information "0000000101010000" in binary code (that is, M=2).

[0061] (1) The creating device 11 creates a watermark graphic element.

[0062] First select a company's logo image; then use an image processing tool (such as Photoshop, etc.) to normalize the logo image to a fixed size, that is, adjust the width and height of the image to a fixed size by compressing / stretching. Then the color of the logo pattern normalized to a fixed size is lightened to obtain an image with a translucent effect, which is used as the watermark graphic element T in this embodiment 1 .

[0063] (2) The rotating device 12 copies N-1 copies of the watermark graphic element created by the creating device 11, and...

Embodiment 2

[0072] In this embodiment, a semi-transparent watermark is embedded in the PDF document, and the watermark graphic element is a group of 8 images containing the name of the hospital "Peking University People's Hospital", respectively T 1 , T 2 ,...,T 8 ,Such as image 3 shown. T 1 is an image containing the character "North", T 2 For an image containing the character "京", ..., T 8 is an image containing the character "园". The hidden information that needs to be carried in the watermark is binary information "000000010101000011001001101111011100101110111101110110110111100110111111". Embed the watermark in the Figure 6a in the background of the document shown.

[0073] (1) The creating device 11 creates a watermark graphic element.

[0074] First select the image T corresponding to each character in "Peking University People's Hospital" 1 , T 2 ,...,T 8 . then T 1 to T 8 Images normalized to a size of 64×64 pixels. The colors of the eight normalized images are t...

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Abstract

The invention discloses an embedding and extraction method of a visible watermark carrying hidden information and a system thereof. A method of embedding a watermark comprises the following steps: making K watermark primitives; making N-1 copies of each watermark primitive, rotating each copy of watermark primitive with a certain angle, and obtaining K groups of candidate watermark primitives comprising N different rotation angles; establishing a corresponding relation between each group of candidate watermark primitives and M-ary system code values of information to be hidden, and embedding a candidate watermark primitive corresponding to each bit information to be hidden into a document. A method of extracting hidden information in a watermark comprises the following steps: obtaining a visible watermark image; obtaining a rotation angle of each watermark primitive in the visible watermark image; according to the corresponding relation between each group of the candidate watermark primitives and the M-ary system code values of the information to be hidden, extracting the hidden information corresponding to the rotation angle of the watermark primitive. According to the method and the system in the invention, meaning expressed by an original image in the watermark can be reserved, and abundant coding information can be hidden in the watermark.

Description

technical field [0001] The present invention relates to a watermark embedding and extraction method and system, in particular to a visible watermark embedding carrying hidden information, and a method and system for extracting hidden information in the visible watermark. Background technique [0002] Visible watermarking in digital watermarking is a widely used technology. As the name suggests, visible watermarking refers to the pattern information attached to the carrier that can be directly observed by human eyes. For example, irregular wavy lines on banknotes, passports, and checks; translucent watermarks such as "trial reading" and "proof sheets" in e-books, etc. From the perspective of whether the watermark pattern has intuitive meaning, visible watermarks can be divided into the following two categories. [0003] 1) The watermark has an intuitive meaning. For example, the semi-transparent watermarks such as "trial reading" and "proof sheet" in the above-mentioned e-b...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06T1/00
Inventor 康凯郝佳于权
Owner PEKING UNIV