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Binary image digit water mark embedding, extraction method and device

A binary image and digital watermarking technology, applied in image data processing, image data processing, image communication, etc., can solve the problems of blind extraction of printing copying and scanning attacks, achieve resistance to printing copying and scanning attacks, good visual effects, Highly robust effect

Inactive Publication Date: 2008-02-13
PEKING UNIV +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The present invention provides a method and device for embedding and extracting digital watermarks in binary images to solve the problem that the digital watermark embedding method for binary images in the prior art cannot meet the requirements of resisting printing, copying and scanning attacks and maintaining good visual quality. Blind extraction can be done when extracting effects and watermarks

Method used

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  • Binary image digit water mark embedding, extraction method and device
  • Binary image digit water mark embedding, extraction method and device
  • Binary image digit water mark embedding, extraction method and device

Examples

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Embodiment 1

[0184] As shown in Figure 2, we use the method described in the present invention to embed 24-bit watermark information in a Chinese italic script small four-size text image. The process of watermark embedding and the required parameters have been described in detail above and will not be repeated here. Fig. 5 is the image after embedding the watermark, and Fig. 6A and Fig. 6B are a partial enlargement of the original image and the embedded watermark image. It can be seen that the visual effect of the image after embedding the watermark is good, and it is difficult to see the traces of the characters being modified. In fact, the characters embedded in the watermark are only slightly thicker or thinner, which does not affect the overall frame of the characters. After the image is printed, we scan the printed copy of the paper medium to an electronic file in the computer into a grayscale image format through a scanner, as shown in Figure 7, and then binarize the grayscale image ...

Embodiment 2

[0190] For a text image of a Chinese Song style small four-size character as shown in Figure 14, we use the method described in the present invention to embed 24-bit watermark information into it. The process and required parameters of watermark embedding are the same as those in the previous example and will not be repeated here. Figure 15 is the image after embedding the watermark. Then print, scan and binarize the image to obtain a text image in binary image format, as shown in FIG. 16 . All 24-bit watermark information can be successfully extracted through the watermark extraction algorithm.

[0191] Next, copy the printed paper document, and then scan and binarize the copy to obtain a text image in binary image format, as shown in FIG. 17 . For Figure 17, we can successfully extract all 24-bit watermark information using the watermark extraction algorithm.

[0192] Next, copy the paper document once again, and then convert it into a binary image as shown in Figure 18 t...

Embodiment 3

[0196] For a stamp image as shown in Figure 20 (enlarged twice display, the original image size is 1024 * 1024 pixels, and the original image display size is 4.4cm * 4.4cm), we use the method described in the present invention to embed 15 Bit watermark information. When embedding the watermark, the image is first divided into 20 sectors, and each sector is regarded as a group, so Figure 20 is divided into 20 groups, as shown in Figure 21, which shows Group 1, Group 2 and Group 20. Then calculate the number of black points in each group to obtain a digital signal with a length of 20, group the signal and perform fourth-order Hadamard transformation on each group. Next, watermark embedding is performed according to the algorithm of the present invention and using parity quantization to embed watermark information with a length of 20÷4×3=15 bits, wherein the quantization coefficient K=1500. Figure 22 is the image after embedding the watermark. Then the image is printed and scan...

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Abstract

The invention discloses a method for embedding a digital watermark in a binary image. The method is as follows: part or all of the binary image is divided into at least two image blocks, and the first pixel is obtained according to the number of black pixels in each image block. A digital sequence; grouping the first digital sequence, performing Hadamard transformation on the data in each group to obtain a second digital sequence corresponding to each group; using a quantization method based on a quantization table, the watermark to be embedded Embedding the signal into the second digital sequence to obtain a third digital sequence; performing an inverse Hadamard transformation on the third digital sequence to obtain a fourth digital sequence, and determining the need to change the color in each image block according to the fourth digital sequence number of pixels, select a corresponding number of pixels in each image block, and change the color of the selected pixels. By adopting the invention, the image embedded with the watermark has a good visual effect and can resist printing, copying and scanning attacks.

Description

technical field [0001] The invention relates to the technical field of digital watermarks, in particular to methods and devices for embedding and extracting digital watermarks in binary images. Background technique [0002] The rapid development of digital network technology puts forward new and higher requirements for multimedia copyright protection and content identification. Digital watermarking technology is gradually developed in response to this requirement. The so-called digital watermarking (Digital Watermarking) is to use the insensitivity of human vision or hearing to add some redundant information to multimedia data (such as images, audio, video and other digital signals) to achieve the purpose of information hiding, so that the copyright statement , licensing conditions, etc. for intellectual property protection. The driving force behind the development of digital watermarking technology is to provide copyright protection for multimedia data, but in fact digital...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T1/00G06K9/18H04N1/00G06V30/224
Inventor 李晓龙亓文法杨斌张华程道放
Owner PEKING UNIV
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