Semi-fragile watermarking method for color image tamper localization and recovery

Abstract

The invention relates to a semi-fragile digital watermarking method for color image tamper localization and recovery. The method comprises the following steps: a grayscale version of an original image is partitioned into blocks and decomposed by wavelet, a binary watermark containing an authentication watermark and a recovery watermark is generated from each image block by loss compression, and the binary watermark is embedded into other image blocks by automorphism mapping; tampered image blocks are localized by the watermark extracted from each image block when the image is authenticated; and a recovery watermark is extracted from other corresponding blocks to recover the original image by decompression as for tamped parts. The method can help process color images, causes the watermarks embedded in the images to be capable of resisting JPEG compression, fuzziness and sharpening, and can localize malicious tampering with the precision of 8*8 pixels, and provide grayscale image recovery of the tampered regions.

Description

technical field [0001] The invention relates to the technical field of image authentication, in particular to a semi-fragile digital watermark method for color image tampering, location and restoration. Background technique [0002] At present, in many practical applications, photos are the carrier that can best record the real situation. However, because the modification of digital images is too easy and verification is difficult, digital photos cannot play a role in serious applications such as forensics and archiving. Therefore, digital image authentication is required to ensure the authenticity of digital images. There are two types of digital image authentication: digital signature and digital watermark. Among them, digital watermark technology is more suitable for image authentication because it does not require additional space to store authentication information. [0003] There have been some researches and methods of image authentication based on digital watermarki...

AI Technical Summary

Problems solved by technology

[0003] There have been some researches and methods of image authentication based on digital watermarking in the prior art, but there are certain deficiencies: the digital image storage of existing image devices (including digital cameras) generally adopts the JPEG lossy compression method, and the current algorithm It is rarely resistant to lossy compression, and it is even more difficult to resist blurring and sharpening, which are beneficial to image practical applications; at the same time, most of the existing results can only locate the tampered part of the image, but cannot restore it; in addition, Most of the current methods focus on grayscale images, and there is no special treatment for commonly used color images, which neither utilizes the redundancy of color images nor greatly limits the application range of image authentication.

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