基于小波变换的用于医学图像的半脆弱水印算法

摘要

According to the speciality of medical images, this paper proposes a semi-fragile watermarking algorithm applied for medical images. The recovery watermark and authentication watermark are embedded into the Hypo-LSB and LSB of the primitive image respectively.The high 6 bits of the primitive image are conducted wavelet transform, and then the recovery watermark is obtained from the quantification and chaotic scrambling of the low-frequency wavelet coefficients and is embedded into the Hypo-LSB of the image. The small volume of information is embedded into LSB of the primitive image to generate authentication watermark. Experiments result shows that the proposed algorithm can locate accurately the position where the primitive image is tampered, and can also restore the region with tampered contents.The authentication watermark in this algorithm can authenticate the medical images effectively. So the algorithm can meet the special request of the medical image.%针对医学图像的特殊性,提出了一种应用于医学的半脆弱水印算法.原始图像的次低位和最低位分别嵌入恢复水印和认证水印.原始图像的高6位进行小波变换,低频系数经量化和混沌置乱后生成恢复水印,将其嵌入到图像的次低位.小容量信息嵌入到原始图像的最低位,生成认证水印.实验结果表明该算法可以准确定位原始图像被篡改的位置,并能对内容被篡改的区域进行恢复.算法中的认证水印能够对医学图像进行有效地认证.该算法能够较好地满足医学图像特殊性的要求.