医学图像可逆数字水印防溢出处理研究

针对医学图像数字水印嵌入过程中出现的大量溢出现象，对文献中提及的几种常见防溢出算法——module一256、位置映射和直方图压缩方法进行了对比实验。实验结果给出了三种方法对可逆水印算法的容量和图像质量造成的影响，证明了直方图压缩方法的优越性。分析指出防溢出算法是医学图像可逆数字水印性能的关键，其算法选择取决于具体的可逆水印算法和医学载体图像的不同形态。

Study on preventing overflow and underflow of reversible digital watermarking for medical images.

In order to effectively solve the overflow and underflow problems during watermark embedding for medical images, three common methods of preventing overflow and underflow mentioned in literatures, including module-256, location map and histogram narrowing have been tested. The experimental results give the effects brought by different three methods to reversible watermarking with respect to several aspects including embedding capacity and image quality and demonstrate the priority of histogram narrowing method. Analyses show the preventing overflow and underflow algorithm is the key step to ensure the per- formance of lossless watermarking, and its choice depends not only on the specific reversible watermarking approach but also on image＇ s different modality specificities.