关键词： 置乱技术, DCT变换, SVD变换, 剪切攻击

Abstract: In order to improve the anti-attack capability  of watermarking system against cropping attack, this paper presents an anti-cropping watermarking algorithm based on multi-transform domain. The DCT transform is carried out on each segmentation region of the host image and the maximum coefficients of each segmentation region are extracted to form a new matrix. The encrypted watermark information is then embedded into the singular value transformation domain of this matrix. Experiments show that the algorithm can not only fully resist the single cropping attack, it also has  strong resistance to the joint attack of conventional image processing and local cropping. Even after multiple joint geometric attacks, it can still extract clear watermarks.

Key words: arnold scrambling, discrete cosine transform, singular value decomposition, cropping attack