关键词: 图像认证, 半脆弱数字水印, 双重变换域, 篡改检测, 篡改定位

Abstract: A semi-fragile image watermarking algorithm is introduced combination of Discrete Cosine Transform(DCT) and Discrete Wavelet Transform (DWT) domains .The algorithm takes advantage of the predominance of extracting image features in DWT and the characteristic that DCT is integration in the procedure of JPEG lossy compression. Tamper detection and tamper localization are realized effectively because of a tamper assessment function is designed and no host image is needed in watermarking extraction. The security of the system is ensured because of a logistic chaos sequence is used for encrypting the watermarking. Experimental results show that the proposed scheme is robust against normal image operations such as JPEG lossy compression and is high sensitive against intentional tampering. Moreover, it can locate the tampered area exactly.

Key words: image authentication, semi-fragile watermarking, dual transform domains, tamper detection, tamper localization