【摘要】 为确保医学图像的完整性与安全性，提出一种基于奇异值分解的分块半脆弱水印医学图像算法，具备定位图像篡改区域以及图像自恢复两种功能。该算法将图像按4×4大小分块，并将水印嵌入位置分为块认证位和自恢复位两种，其中块认证位用于认证每个块，确保该块被篡改时能被识别出来；自恢复位则用于实现图像被篡改后的自恢复。将分块通过奇异值分解生成块认证位，同时将块划分为2×2的块，计算它们的5MSB平均值以生成自恢复位。仿真实验结果表明，所提算法的PSNR指标均在50 dB以上，大部分篡改攻击的Rfa和Rfd接近于0，且自恢复图像PSNR指标在30 dB以上。所提算法具有较好的透明性，能准确检测大部分篡改攻击，且自恢复图像质量良好。更多还原

【Abstract】 To ensure the integrity and security of medical images, a block based semi fragile watermarking medical image algorithm based on singular value decomposition is proposed, which has two functions: locating image tampered areas and image self recovery. This algorithm divides the image by 4 × Divide the watermark into blocks of 4 sizes and divide the embedding position into two types: block authentication bit and self recovery reset. The block authentication bit is used to authenticate each block, ensuring that it can be recognized when tampered with; Self recovery reset is used to achieve self recovery of images after being tampered with. Generate block authentication bits through singular value decomposition for block partitioning, while dividing the block into 2 × Calculate the average value of 5MSB for blocks of 2 to generate self recovery reset. The simulation experiment results show that the PSNR index of the proposed algorithm is above 50 dB, and for most tampering attacks, the Rfa and Rfd are close to 0, and the PSNR index of the self recovered image is above 30 dB. The proposed algorithm has good transparency, can accurately detect most tampering attacks, and has good self recovering image quality.更多还原