为保证水印图像质量并提高嵌入水印数据量,该文提出一种基于整数变换的自适应图像可逆水印方法。该方法定义了一种新的一般化整数变换算法,对于任意像素点组成的图像块向量进行简单的整数变换后,将产生一定的冗余数据可用于嵌入水印数据。该方法进一步根据图像块向量自身方差大小自适应选择参数m值进行整数变换,在平滑图像块中嵌入更多数据,同时避免复杂图像块中引入较大失真,从而保证具有较高的嵌入容量和较好的水印图像质量。与同类算法对比的实验结果表明,该方法增大了最大数据嵌入容量,以Lena为宿主图像时有效载荷可达2.36 bpp。该文整数变换算法运算简单,通过自适应选择参数进行整数变换并嵌入数据可保证水印图像质量并实现较大的有效载荷。
To ensure the quality of watermarked image and improve the embedding capacity of watermarkings, an adaptive image reversible watermarking method based on interger transform is proposed in this paper, which defines a new generalized integer transform algorithm. Through the use of the method the image blocks of arbitrary sized are transformed, producing certain redundancy data that can be used for watermarking embedding. In addition, the parameter m used for integer transform is adaptively selected according to the variance of every image block, hence allowing for embedding more data bits into the smooth blocks while avoiding large distortion generated by complex ones, and thus the algorithm ensures a higher embedding capacity and better quality of watermarked image. Compared with similar algorithms, the experimental results show that the proposed method has larger maximal embedding capacity and taking Lena as a host image, the real payload can reach up to 2.36 bpp. The proposed integer transform algorithm is simple;through adaptively interger transforming and data embedding, the quality of watermarked image can be assured and the method offers a large real payload.