基于图象特征的小波域水印算法

提出一种基于图象特征点的小波变换域第二代水印算法.首先对图象作小波变换,其中最低频成分是图象的粗尺度(低分辨率)逼近,从中提取出图象的特征点;然后在特征点对应的所有高频系数中嵌入水印.水印检验不需要原始图象,但需要原始图象的特征点位置信息,计算特征点对应的所有高频系数与嵌入水印的互相关,利用门限值检验水印是否存在. 实验证明该算法对通常的图象处理有很强的鲁棒性,对有损压缩的鲁棒性尤为突出,而且对几何变换也有一定鲁棒性.

IMAGE-FEATURE BASED WAVELET DOMAIN WATERMARKING

An image feature based second generation watermarking scheme is proposed in this paper.A host image is firstly transformed into wavelet coefficients and features are extracted from the lowest approximation.Then a watermark sequence is inserted in all high frequency coefficients corresponding to the extracted featured approximation coefficients.Original host image is not needed in watermarking detection,but the featured approximation coefficients position is necessary for robust detection.The correlation between the embedded watermark and all high frequency coefficients of a possibly corrupted watermarked image corresponding to the approximate coefficients at the same position as the original featured approximation coefficients is calculated and compared to a predefined threshold to see if the watermark is present.Experimental results show the watermark is very robust to common image processing,lossy compression in particular.