A novel postprocessing algorithm for concealing spatial block errors in block-based coded images is proposed using block classification with a variable operating region (VOR). In the proposed algorithm, a missing block is classified as flat, edge, or complex based on local information from the surrounding blocks which is extracted using a Sobel operation in a VOR. In this case, the VOR is determined adaptively according to the number of edge directions in the missing block. Using the classification, the flat blocks are then concealed by the linear interpolation (LI) method, the edge blocks are. concealed by the boundary multi-directional interpolation (BMDI) method, and the complex blocks are concealed by a combined linear interpolation and boundary matching (CLIBM) method. Experimental results demonstrated that the proposed algorithm improved the PSNR and visual quality of the concealment for both original images and JPEG compressed images, and produced better results than conventional algorithms.
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机译：该文提出一种利用可变操作区域（VOR）进行分块分类的后处理算法，用于隐藏基于分块的编码图像中的空间分块误差。在所提出的算法中，缺失块根据周围块的局部信息被分类为平面、边缘或复杂，这些信息是在 VOR 中使用 Sobel 运算提取的。在这种情况下，VOR 是根据缺失块中的边沿方向数量自适应确定的。使用分类，然后通过线性插值 （LI） 方法隐藏扁平块，边缘块被隐藏。采用边界多向插值（BMDI）方法进行隐藏，采用线性插值和边界匹配相结合（CLIBM）方法对复杂块进行隐藏。实验结果表明，所提算法对原始图像和JPEG压缩图像的隐蔽性均有较好的PSNR和视觉质量，效果优于传统算法。
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