关键词: 数字水印, 零水印, 离散小波变换, 非负矩阵分解, 鲁棒性

Abstract: In order to solve the problem of perceptible quality degradation and the inherent conflict between imperceptibility and robustness, a novel image watermark algorithm based on Non-negative Matrix Factorization（NMF） and Discrete Wavelet Transform（DWT） is proposed in this paper. The processes of watermark embedding include three steps：the original image is divided to not-overlap image blocks and then decomposable coefficients are obtained by three-level DWT in every image blocks. Secondly the low-frequency coefficients of block images are selected and then approximately represented as a product of a base matrix and a coefficient matrix using NMF. Finally the feature vector represent original image is obtained by quantizing coefficient matrix, and then the copyright information is embedding by calculating the watermark and feature vector. Experimental results show that the scheme is robust against common signal processing attacks, meanwhile security of the algorithm is guaranteed by using secret keys.

Key words: digital watermarking, zero-watermarking, discrete wavelet transform, non-negative matrix factorization, robust