Digital watermark embedding and extracting method based on multi-level wavelet coefficient weighting and quantification

Abstract

The invention provides a digital watermark embedding and extracting method based on multi-level wavelet coefficient weighting and quantification. The method comprises the steps that the initial values and parameters of a watermark encryption link and a watermark embedding link are generated through the MD5 value of a cover image and a secret key given by a user, chaotic mapping is driven to generate a 2-value paseudorandom matrix to encrypt a 2-value watermark, an intermediate parameter generated by the chaotic mapping is applied to coefficient selection of the watermark embedding link, hence, the watermark encryption link and the watermark embedding link can be tightly coupled with the cover image and the secret key given by the user, and watermark and watermark embedding safety is improved. According to the method, a multi-level wavelet coefficient weighting embedding strategy is adopted, weighting is set according to the arithmetic average of wavelet coefficient absolute variations compressed by a JPEG, in this way, the wavelet coefficient weights at different levels are different, the influence of one single wavelet coefficient on the watermark is reduced, and the image visual quality and the watermark embedding safety are further improved; in the watermark extracting process, the watermark extracting quality can be improved by filtering out isolated dark spots, and therefore the recovery errors of the watermark are effectively reduced.

Description

technical field [0001] The invention belongs to the cross-research fields of information security and digital image signal processing, and relates to a digital watermark embedding and extraction method, in particular to a digital watermark embedding and extraction method based on multilevel wavelet coefficient weighting and quantization. Background technique [0002] The development of multimedia and network technology enables people to obtain various digital image information more conveniently. Digital images have the advantages of easy storage, easy transmission, and easy operation, but at the same time, pirates can make unauthorized copies and dissemination of them; malicious attackers can easily tamper or forge them, which is easy to cause serious consequences and lead to major economic losses. [0003] For image information security, people have proposed a variety of methods, such as: ① digital image encryption technology that converts plaintext images into ciphertext ...

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Problems solved by technology

[0008] However, the parametric wavelet is used to determine and influence the embedding position of the watermark to improve the security of the watermark embedding strategy. None of the above methods have been analyzed theoretically, and they are only based on experimental examples.

Experiments have shown that the sensitivity of parametric integer wavelet to parameter value changes is difficult to meet the actual needs. When the parameters of parametric wavelet are changed, the embedded watermark can still be approximately extracted, so the security of the embedded watermark is still difficult to guarantee.

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