一种低码率下简单有效的环路滤波方法

针对低码率编码情况下块效应严重的现象，提出一种环路滤波去除块效应的算法.该算法基于图像
特征在时域和频域对应的原理，利用变长码编码特点，在频域分析编码块的特性，自适应选择不同强度和
模式的滤波算法，从而保证滤波后图像的真实性.在滤波算法的设计过程中又选用了合适的参数，以进一
步降低滤波过程中增加的计算量.仿真结果表明，该算法提高了重构帧的峰值信噪比(PSNR)值和视觉效果
；同时作为参考帧的重构帧，其质量的提高能减少运动估计的运算开销，以抵消采用环路滤波而引入的计
算量，保证了编码过程的实时性.

Simple and efficient loop-filtering for low bit-rate coding

A loop-filter for removing the block effect based on the characteristics of variable length coding and the corresponding principle of picture character behavior both in time and frequency domain was proposed. The loop-filter analyzes the coded frame identity in DCT domain, chooses an appropriate filtering mode to adaptively maintain the authenticity of the reconstructed frame, and uses some appropriate and simple parameters to reduce the computational complexity. Simulation results showed that the proposed method improves the reconstructed frame quality, which saves the cost expended in motion estimation to countervail the burden caused by filtering, and ensrues the real-time processing of encoding.