关键词: 数字水印, Hilbert扫描, 小波域, 奇异值分解（SVD）

Abstract: In order to improve the security，robustness and invisibility of a watermark，an image watermarking technology is proposed，based on the wavelet domain singular value decomposition and Hilbert scanning.The watermark signal is a binary watermark image.First，do a wavelet transform to the original image，then block to the low-frequency components，and for all image blocks do singular value decomposition.SVD preserves both one-way and non-symmetric properties.According the characters of the orthogonal matrix after SVD，an adaptive image watermarking scheme is given by taking full advantage of Hilbert scanning.The threshold，which is used to modify the selected coefficients，is decided by the statistical properties of local blocks.The modification of coefficients is controlled by these two thresholds so as to obtain the optimal tradeoff between the invisibility and the robustness.At the same time，the watermark can be extracted without original image.It is truly blind watermark algorithm.The experimental results show that the proposed algorithm is effective，which is very robust to common image processing operations.

Key words: Digital Watermark, Hilbert Scanning, Wavelet Domain, Singular Value Decomposition（SVD）