Image watermarking method based on DCT direct-current coefficients of Weibull model

Abstract

The invention discloses an image watermarking method based on the DCT direct-current coefficients of the Weibull model. In the watermark embodiment stage, discrete cosine transform (DCT) is conducted on non-overlapping 8*8 image blocks in an image block by block, watermark signals are embedded in the direct-current coefficients of all the DCT blocks according to a multiplication rule, and discrete cosine transform is conducted on all the DCT blocks where watermarks are embedded so that a watermarked image can be obtained. In the watermark extraction stage, discrete cosine transform is conducted on the non-overlapping 8*8 image blocks in the watermarked image block by block, the direct-current coefficients of all the DCT blocks are selected, modeling is conducted according to the Weibull model, model parameters are estimated, and watermark detection is conducted through a specific detector. The image watermarking method overcomes the defect that modeling can not be conducted on the discrete cosine transform through a traditional model, and watermark detection does not rely on the original image.

Description

technical field [0001] The invention relates to a method for embedding and detecting a watermark on DCT coefficients, and belongs to the technical field of information hiding. Background technique [0002] Discrete Cosine Transform (DCT) has a large number of applications in science and engineering. Taking images and videos as examples, discrete cosine transform is used in both the still image coding standard JPEG and the moving image coding standard MPEG. In the field of digital image watermarking, people pay less attention to DCT coefficients than to AC coefficients. An important factor is that the commonly used models cannot model DCT DC coefficients. For example, the general Gaussian distribution or Cauchy distribution are bilateral distribution models. , while the DCT coefficient is non-negative, and the data are distributed on the right side of the origin. Since the result of most watermarking attacks is the distortion of the AC coefficient, that is, the details of t...

AI Technical Summary

Problems solved by technology

The advantage of quantization index modulation technology is that it can embed a large amount of data, but the robustness of this technology depends on the minimum distance between two quantization points on the quantization constellation diagram, so the robustness is generally not as good as the method based on maximum likelihood detection; at the same time, the study found that QIM It will change some statistical properties of the watermark carrier, such as the gradient energy of the image, histogram features, and wavelet statistical features, etc., easily exposing the existence of the watermark

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