关键词: 半脆弱水印, 图像认证, Bandelet变换, Turbo码, 斜变换

Abstract: Concerning general image operations and attack method, the paper proposed a new semi-fragile watermarking algorithm. In this algorithm, the recovery bits generated from the compressed original image were embedded into the Least Significant Bits (LSB) of the watermarked image, then the switch coefficients coded by Turbo code after second generation Bandelet transform were embedded in midfrequency blocked regions after slant transform. Authentication could be realized and tampers could be located through comparison between error codes generated by Turbo code and coefficients of Bandelet transform. The experimental results show that the algorithm has enough robustness to general image operations, and can detect and locate the place being maliciously tampered accurately, and has good ability to recover the lost image content.

Key words: semi-fragile watermark, image authentication, Bandelet transform, Turbo code, slant transform