关键词: 图像处理, 图像水印, 压缩, 安全, 加密, 信号处理

Abstract: A new technique combining spatial domain and frequency domain is proposed, which can provide more watermarks in the condition of reducing the distortion of watermark image. The watermark is divided into two parts: the spatial domain and the frequency domain, and embedded into the spatial domain and the frequency domain according to the user's needs or the importance of the data respectively. Experimental results provide the comparisons when different sized watermarks are embedded into the grayscale image. The proposed combinational image watermarking possesses the following advantages. More watermark data can be embedded into the host image, so that the capacity is increased. The watermark is divided into two parts in spatial domain and frequency domain makes the degree of protection double. The splitting strategy can be designed to be more complex in order to make the embedded watermark unrecoverable. In addition, in order to enhance the robustness, a random permutation of the watermark is used to combat the attacks of signal processing such as image crops.

Key words: Image processing, Image watermarking, Compression, Security, Encryption, Signal processing