一种基于块效应强度检测和测量的新型图像质量评价方法

摘译目前,大部分图像压缩标准使用基于块的变换编码,图像压缩过程中会产生各种压缩效应。其中,块效应是降低图像压缩质量的最常见的问题之一。对块效应进行量化的图像质量客观评价方法可有效地降低块效应的发生,同时也可优化整个图像压缩系统,例如,其可以用于图像预处理（检测和有选择地补偿块效应）中。

A New Image Quality Assessment Method to Detect and Measure Strength of Blocking Artifacts

Block based transform coding is one of the most popular techniques for image and video compression. However it suffers from several visual quality degradation factors, most notably from blocking artifacts. The subjective picture quality degradation caused by blocking artifacts, in general, does not agree well with the popular objective quality measure such as PSNR. A new image quality assessment method that detects and measures strength of blocking artifacts for block based trans- form coded images is proposed. In order to characterize the blocking artifacts, we utilize two observations： if blocking arti- facts occur on the block boundary, the pixel value changes abruptly across the boundary and the same pixel values usually span along the entire length of the boundary. The proposed method operates only on a single block boundary to detect bloc- king artifacts. When a boundary is classihed as having blocking artifacts, corresponding blocking artifact strength is also computed. Average values of those blocking artifact strengths are converted into a single number representing the subjective image quality. Experiments on various JPEG compressed images with various bit rates demonstrated that the proposed bloc- king artifacts measuring value matches well with the subjective image quality judged by human observers.