关键词: 数字水印, 双树复小波变换, C均值聚类, Hilbert曲线置乱

Abstract: In order to improve the robustness of digital watermarking images, this paper proposes an algorithm of image digital watermarking based on Dual Tree Complex Wavelet Transform（DT-CWT） domain and Hard C-Means cluster（HCM）. The original image is decomposed by one level DT-CWT. The watermark embedding location is identified adaptively by applying HCM in the two low frequency sub-band which is produced by DT-CWT. The binary watermark is disposed after Hilbert curve scrambling transformation and dimension reduction. A one-dimensional signal sequence is formed. Using image itself local relevance, this paper adjusts the embedding strength and modifies wavelet coefficient value, to realize the one-dimensional signal sequence embed in the watermark embedding location. The finding is that this method is invisible and robust against various geometric attacks such as compression, cropping, noise adding, filters, and so on.

Key words: digital watermarking, Dual Tree Complex Wavelet Transform（DT-CWT）, hard C-means cluster, Hilbert curve scrambling