ROI和轮廓波结合的医学图像盲水印算法

A blind watermark algorithm for medical images using ROI and contourlet

针对现有水印方法不能很好地实现信息隐藏和认证同时进行的不足,提出一种基于ROI和轮廓波变换域的DICOM图像水印技术.该技术应用改进的可逆差分扩展方法在DICOM图像的背景区域嵌入水印w1,即患者的隐私信息和感兴趣区域的子块均值.水印w1嵌入后,在图像的轮廓波域中能量较大的高阶方向子带的位置上,采用轮廓波系数与8邻域均值比较的方法嵌入认证水印w2.算法实现了水印图像的盲提取,同时具有对感兴趣区域的篡改进行定位并修复的能力,保障诊断时图像的真实性和完整性.仿真实验表明,该技术具有较强的数据信息隐藏能力和较好的抗攻击能力.

A blind watermarking algorithm which combined region of interest （ROI） with Contourlet transform has been proposed in view of the existing watermark algorithms which can not realize simultaneously the information hid- ing and authentication for digital imaging and communications in medicine （DICOM） images. The watermark w1 consisted of patient＇s private information and the subblocks means of ROI was embedded into background （BG） of DICOM image using a reversible technique based on modified difference expansion. After that authentication water- mark w2 was embedded into the high-order greater energy directional subbands of the first watermarked image＇s cont- outlet domain using the method of comparing the contoutlet coefficient and its 8-neighborhood mean. The scheme is a blind watermarking algorithm, and is able to locate and recover tampered regions with a very good visual quality to ensure image authenticity and integrity for the scheme has a high capacity of data hiding diagnosis. Theoretical analysis and numerical experiments show that as well as anti-attack ability.