Research on digital watermark of combination of wavelet and balanced multiwavelet transform
Based on wavelet and balanced multiwavelet transformation, a watermarking algorithm for gray image is proposed in this paper. First the low frequency area is obtained by decomposing the original image by wavelet, which is further decomposed by balanced multiwavelet. Then the high-frequency coefficients with highest scale are chosen as watermark embedded carrier. The normalization of gray watermarked image has greatly reduced the amount of data. The algorithm adopts additive principle to embed watermark. This algorithm has the advantages of wavelet which can concentrate energy easily in the low frequency area and characters of balanced multiwavelet transform which can distribute energy averagely. This algorithm is generally applicable of the gray watermark system. Experimental results show that this algorithm has a good performance of watermark both in the robustness and the invisibility.