Guo Xiaotao, Zhuang Tian-Ge
Department of Biomedical Engineering, Shanghai Jiaotong University, Shanghai 200240, China.
J Digit Imaging. 2009 Mar;22(1):53-64. doi: 10.1007/s10278-007-9043-6.
This paper presents a lossless watermarking scheme in the sense that the original image can be exactly recovered from the watermarked one, with the purpose of verifying the integrity and authenticity of medical images. In addition, the scheme has the capability of not introducing any embedding-induced distortion in the region of interest (ROI) of a medical image. Difference expansion of adjacent pixel values is employed to embed several bits. A region of embedding, which is represented by a polygon, is chosen intentionally to prevent introducing embedding distortion in the ROI. Only the vertex information of a polygon is transmitted to the decoder for reconstructing the embedding region, which improves the embedding capacity considerably. The digital signature of the whole image is embedded for verifying the integrity of the image. An identifier presented in electronic patient record (EPR) is embedded for verifying the authenticity by simultaneously processing the watermarked image and the EPR. Combining with fingerprint system, patient's fingerprint information is embedded into several image slices and then extracted for verifying the authenticity.
本文提出了一种无损水印方案，即可以从加水印的图像中精确恢复原始图像，目的是验证医学图像的完整性和真实性。此外，该方案能够在医学图像的感兴趣区域（ROI）不引入任何嵌入引起的失真。采用相邻像素值的差值扩展来嵌入若干比特。故意选择一个由多边形表示的嵌入区域，以防止在ROI中引入嵌入失真。仅将多边形的顶点信息传输到解码器以重建嵌入区域，这大大提高了嵌入容量。嵌入整个图像的数字签名以验证图像的完整性。通过同时处理加水印的图像和电子病历（EPR）来嵌入电子病历中呈现的标识符以验证真实性。与指纹系统相结合，将患者的指纹信息嵌入到几个图像切片中，然后提取以验证真实性。
