Image Watermarking Method Based on Wavelet Transform
基于小波变换的图象水印嵌入方法

As a new technique applying to protecting the copyright of digital productions, the digital watermark technique has drawn extensive attention. A method of embedding the watermark in digital images based on the discrete wavelet transform is proposed. The watermark used here is not the conventional patterns such as a pseudo-random sequence or a bit stream but a text watermark. The information which the text watermark contains is abundant and intuitionistic, also the watermark is robust. To ensure the security of the watermark and make the watermark be hard to be extracted, the watermark is scrambled with Arnold scrambling transformation before embedded into the original image. According to the different characteristics of the high and the low frequency components of the wavelet coefficients of the original image, more watermark information is embedded in the high frequency components while less information in the low ones. That is to say, by using the hierarchical structure of the wavelet, the watermark is repeatedly embedded in various places. Moreover, experimental results have proved that the method is robust enough to some image degradation process such as cropping, JPEG compression and sharpening etc. So it is effective.