基于图像块分类的篡改定位和恢复水印算法

针对现有方法所提取的特征值不能灵活适应图像 的纹理变化导致被篡改图像恢复质量不高的问题, 提出一种根据图像块纹理特征进行块类型划分的篡改定位和恢复水印算法。首先把宿主图像 分3×3大小的 子块,再利用方差和Canny边缘检测算子将图像子块划分为简单块、复杂块和边缘块；然后 根据图像子块 类型,自适应地生成水印信息；最后采用Torus自同构映射方式找到水印嵌入位置,并且对 篡改区域进行恢 复时根据图像子块类型自适应的恢复。当图像遭到篡改时,采用本文算法恢复图像的平均峰 值信噪比(PSNR)较现有方 法提5.60%左右。实验表明,本文算法能够对图像纹理复杂区 域生成更精确的 恢复信息,有效提高了图像篡 改区域的恢复质量,同时降低含水印图像失真。算法适用于医学、军事和卫星等领域。

Image blocks classification watermarking method for tamper detection and recovery

As for the eigen value extracted by the existing methods could not fle xibly adapt to the change of image textures,leading to lower recovery quality of tampered images,an image blocks classification watermarking method for tamper detection and recovery is proposed.Firstly of al l,the original host image is divided into 3×3sub blocks;then the variance of sub blocks and Canny edge det ection algorithm are adopted to mark these sub blocks into smooth blocks,rough blocks and edge blocks.According to these sub image types,the eigen value could be adaptively generated.Finally,the Torus automor phismis algorithm is used to find the position of mapping blocks.In the meantime,the tampered images could be re covered adaptively based on sub images type.If the image has not been tampered,the peak signal-to-noise ratio (PSNR) can be improved by 5.60% compared with existing method.Experimental results show that compared with previous similar schemes,the proposed method can more accurately produce recover y watermarking information,make better improvement on the recovery quality of the tampered image and effectively reduce the distortion of watermark ing image.The presented method can be applied in many fields,including the areas of medicine,military,and satellites.