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An adaptive method for extending, transforming and dithering modulation of watermarking

An adaptive and watermarking technology, applied in the fields of instruments, computing, electrical components, etc., can solve problems such as the impossibility of obtaining a large quantization step size, loss of STDM robustness, and non-compliance with the characteristics of perceptual systems.

Inactive Publication Date: 2007-05-23
PEKING UNIV
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Problems solved by technology

However, it uses a fixed quantization step size, and the amount of modification to each component of the host signal is also random, which does not conform to the characteristics of the human perception system; as a result, in order to meet the requirements of watermark imperceptibility, the quantization step size cannot be obtained very large. Large, thus losing the robustness of STDM, it is difficult to obtain an ideal compromise between the two

Method used

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  • An adaptive method for extending, transforming and dithering modulation of watermarking
  • An adaptive method for extending, transforming and dithering modulation of watermarking
  • An adaptive method for extending, transforming and dithering modulation of watermarking

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Embodiment 1

[0082] Watermark Carrier A o For an image signal, realize an adaptive STDM watermark embedding method, the whole process is as shown in Figure 1, including the following steps:

[0083] (1) From A o The block DCT (DCT: Discrete Cosine Transform) domain extracts the host signal x. A oDivide into multiple non-overlapping sub-blocks, each block contains 8×8 pixels, and then perform DCT transformation on each block. Perform zigzag sorting on the 64 DCT coefficients in each block, and select 62 DCT coefficients with ordinal numbers ranging from 3 to 64. Arrange all selected DCT coefficients into a large sequence as the host signal of the watermark. Then scramble the extracted host signal according to a certain random order. The generation of this random order depends on the watermark key K, and the final generated signal is recorded as x, and its length is N. This step is realized by extracting the host signal device, as shown in Figure 2 and Figure 3 .

[0084] (2) In this e...

Embodiment 2

[0128] The difference from Example 1 is that the original signal A o It is an audio signal with a length of 10 seconds, and the time domain has a total of 4.4×10 4 sample, the specific implementation steps are as follows:

[0129] In step (1), from A o Extract the host signal x in the frequency domain of . Calculate A first o The short-time Fourier transform and energy spectrum, and then use the Garcia auditory model (R.A.Garcia.Digital watermarking of audio signals using a psychoacoustic auditory model and spread spectrum theory.Proc of 107 th AES Convention, New York, 1999, 1-42) calculates the maximum amplitude that the human ear cannot detect at each frequency point. In order to be consistent with the previous one, we also call it JND. Select the frequency points whose energy spectrum is smaller than the square of JND, count the number of these frequency points and generate a zero vector of equal length as the host signal x of the watermark, that is, x=θ.

[0130] In ...

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Abstract

It is an adaptive expanding transform jitter modulation watermarking method. The expanding transform jitter modulation watermarking has the advantages both quantitative index modulation watermarking and spread spectrum communication system, and it has a good performance against attack. However, the original STDM method uses the fixed quantization step, which takes no account of human perceptual model, so its performance is greatly limited. The invention introduces a human perception model / signal quality evaluation method to the original STDM, used to measure the distortion introduced by watermarking and compute a weighted sequence, and the use of weighted plastic watermarking idea changes host signals, to make the local variable capacity of the host signal apply for the human perception system; re-designing the quantization step to meet the distortion conditions determined by un-perceptibility. Using the method described in the invention, the embedded watermark can fully use the local characteristics of carrier signal, adaptive design the quantization step, greatly enhance the watermark robustness, and at the same time achieve a good watermark un-perceptibility.

Description

technical field [0001] The invention belongs to the technical field of digital watermarking, relates to a watermark embedding method, in particular to an adaptive extended transformation dither modulation watermarking method. Background technique [0002] The past decade has seen an explosion in the use and distribution of digital media information. With the help of the Internet, people can easily publish and obtain various digital information, including images, audio, video and text, as well as many online services. But at the same time, piracy has become easier. Unrestricted copying and uncontrollable transmission make digital content copyrightless. The management and protection of digital content has become an urgent problem to be solved in the industry. [0003] Digital watermarking is an emerging copyright protection technology. It studies how to hide a certain amount of additional information in the original data, such as the ownership of the work, the right to use ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T1/00H04N1/32
Inventor 朱新山
Owner PEKING UNIV
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