Method for generating and authenticating digital image tampered content recoverable variable capacity watermarks

Abstract

The invention discloses a method for generating and authenticating digital image tampered content recoverable variable capacity watermarks, which comprises the following steps of: dividing 2*2 image blocks into smooth image blocks and non-smooth image blocks, extracting 6bit characteristics from the smooth image blocks, extracting 12bit characteristics from the non-smooth image blocks, encryptingthe characteristics of the image blocks to generate image block recovery watermarks, randomly embedding the image block recovery watermarks into other image blocks, and judging the authenticity of the image blocks by comparing the consistency of the characteristics of the image blocks and combining block neighborhood characteristics. For the judged tampered image blocks, different tampering recovery operations are executed in two steps according to whether the corresponding recovery watermarks of the image blocks are tampered to improve the tampering recovery quality. The variable capacity recovery watermarks are generated according to the personal characteristics of the image blocks, and the recovery watermarks are simultaneously used for tampering positioning and tampering recovery, so the watermark embedding capacity is reduced when enough image characteristics are ensured, and watermark-containing image quality and tampering recovery quality are considered; and meanwhile, the security is improved, and known forging attacks such as joint attack, mean attack and the like can be resisted.

Description

Technical field [0001] The invention relates to a method for generating and authenticating an authentication watermark capable of restoring the tampered content of a character image, which is used for detecting the authenticity and integrity of a digital image and recovering the tampered image. Background technique [0002] With the development of computer, digital imaging and network communication technology, digital images have become the main source of people's acquisition and exchange of information and one of the important carriers of information dissemination. The digital storage of images and the emergence of various image processing software have made the editing, modification and synthesis of digital images very simple. Digital image processing technology has improved the display quality of images, but tampering and forging images, such as being used in news media, forensic evidence, scientific discoveries, and other fields, will bring serious consequences to the integri...

AI Technical Summary

Problems solved by technology

There are two most commonly used methods for generating and restoring watermarks: ① Quantization and encoding of important DCT (discrete cosine transform) coefficients of 8×8 image blocks, the disadvantage of which is low positioning accuracy

② The average value of 2×2 image blocks has high positioning accuracy, but it is vulnerable to constant average value attacks and the recovery quality of non-smooth image blocks is not good

But saving the texture features of the image block will increase the watermark capacity, and adding texture features to smooth blocks like B1 is redundant

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