一种改进的基于后处理去除块效应算法

在基于DCT压缩编码系统中,DCT都是基于模块的。即首先将图像分成8×8的像素块,然后对每块进行DCT得到64个DCT系数。但由于是分别对每块进行DCT,块与块之间的相关性被忽略,导致所谓的“块效应”。文中提出了一种改进的基于后处理的去块效应方法。在图像重建时,首先在块与块之间提出了4种模式,包括了3个与频率相关的模式和4个块拐角处的拐角模式。然后对不同模式下采用低复杂度的去块效应滤波器,最后重建图像。不论是视觉效果还是图像质量都有所提升。

An Improved Algorithm for Reducing Blocking Effects Based on Post-processing

In the compression system based on DCT(Discrete Cosine Transform),the DCT is based on the block.Images are first broken down into 8×8 pixels pieces,then it gets 64 DCT coefficients through DCT for each block.Since each block gets DCT respectively,the correlation between blocks are ignored,thus the "Blocking Effects".This paper proposes an improved method for reducing blocking effect based on post-processing.When the images are reconstructed,four modes are proposed for the corner of four blocks,including three frequency-related modes(smooth mode,non-smooth mode,and intermediate mode) and a corner mode.A low computational deblocking filter is then adopted for different mode,and images are reconstructed.Both visual effect and image quality are improved.