基于整数小波的无损数字水印技术

提出基于整数小波的大容量数据嵌入具有无损图像恢复性能的数字水印技术。由于预先压缩灰度直方图的动态范围，因此嵌入数据后的小波反变换的灰度在0～255范围内。该文在小波域最高分辨率区的次低位平面嵌入数据，利用小波的多分辨率、解相关和高压缩率的特点,在图像中嵌入大量数据，并且使之具有视觉不敏感的特性。数据提取后图像能完全恢复。文中的例子说明这个论点是正确的。为获取更高的PSNR，提出两种修改直方图的方法，并通过具体的实验数据比较两者的效果。

Distortionless Digital Watermarking Based on Integer Wavelet

This paper proposes a distortionless digital watermarking algorithm based on integer wavelet transform, which can recover original image without any distortion from the marked image after the hidden data have been extracted. The image histogram modification is used to prevent grayscales from possible overflow/underflow of 0~255 that may take place due to the data embedding. This algorithm hides the data into a middle bit-plane of the integer wavelet coefficients in high frequency subbands. It can embed much more data compared with the existing distortionless data hiding techniques and satisfy the imperceptibility requirement. The algorithm has been applied in a wide range of different images successfully. Experimental results are presented in this paper to demonstrate the validity of the algorithm. To obtain higher PSNR performance at the same time, two histogram-adjustment methods are presented in this paper and experiment data are listed to compare the effects of them.