MC H.264 去块效应滤波器(Deblocking filter) ◆消除由于相邻宏块由不同的运动估计或者量化导致 的人工痕迹。 Whether or not to filter a particular block boundary Whether to apply strong or normal deblocking SIEMENS SIEMENS 21 (ynh,cxh@ustc.edu.cn
{ynh,cxh}@ustc.edu.cn H.264 去块效应滤波器(Deblocking filter) 消除由于相邻宏块由不同的运动估计或者量化导致 的人工痕迹。 Whether or not to filter a particular block boundary Whether to apply strong or normal deblocking 21
MC H.265(HEVC)的去块效应手段之一 SAO:edge offset (EQ) Sample Classification Rules for Edge Offset Four 1-D directional patterns for Category Condition EO sample classification 1 c<a&&c<b 2 (c<a&&c==b)(c ==a &c <b) a 3 (c>a&&c==b)(c=a&&c>b) 4 c>a &&c>b 0 None of the above Category I Category 2 Category 3 Category 4 Positive offsets for EO categories 1 and 2 and negative offsets for a b a c b a c b a b EO categories 3 and 4 sample index sample index sample i dex sample index result in smoothing. a c b sample index sample index Sample Adaptive Offset in the HEVC Standard 22 ynh,cxh @ustc.edu.cn IEEE Transactions on Circuit and System for Video Technology,vol.22,NO.12,Dec 2012
{ynh,cxh}@ustc.edu.cn H.265(HEVC)的去块效应手段之一 SAO: edge offset (EO) 22 Four 1-D directional patterns for EO sample classification Sample Classification Rules for Edge Offset Positive offsets for EO categories 1 and 2 and negative offsets for EO categories 3 and 4 result in smoothing. Sample Adaptive Offset in the HEVC Standard IEEE Transactions on Circuit and System for Video Technology, vol. 22, N0. 12, Dec 2012
MC 傅里叶变换的问题 Gibbs phenomenon The Gibbs phenomenon involves both the Functional approximation of square fact that Fourier sums overshoot at a jump wave using 5 harmonics discontinuity,and that this overshoot does not die out as the frequency increases 1.5 1.0 0.5 0.0 Functional approximation of square -0.5 wave using 25 harmonics -1.0 0.5 1.0 1.5 2.0 1.0 0.8 0.6 0.4 0.2 0.0 Functional approximation of square 80 -60 -40 -20 20 40 60 80 wave using 125 harmonics http://en.wikipedia.org/wiki/File:SquareWave.gif
{ynh,cxh}@ustc.edu.cn 傅里叶变换的问题 Gibbs phenomenon The Gibbs phenomenon involves both the fact that Fourier sums overshoot at a jump discontinuity, and that this overshoot does not die out as the frequency increases. http://en.wikipedia.org/wiki/File:SquareWave.gif
MC Ringing effect JPEG2000 Original JPEG 928 bytes 389 bytes 898 bytes The ringing effect is fundamentally associated with Gibb's phenomenon,and,as such,it is most evident along high contrast edges in areas of generally smooth texture in the reconstruction,and appears as a shimmering or rippling outwards from the edge up to the encompassing block's boundary. A survey of hybrid MC/DPCM/DCT video coding disto tions,Signal Processing 70(1998)247-278 ynh,cxh @ustc.edu.cn http://www.stat.columbia.edu/~jakulin/jpeg/artifacts.htm
{ynh,cxh}@ustc.edu.cn Ringing effect 24 A survey of hybrid MC/DPCM/DCT video coding distortions, Signal Processing 70 (1998) 247-278 http://www.stat.columbia.edu/~jakulin/jpeg/artifacts.htm The ringing effect is fundamentally associated with Gibb’s phenomenon, and, as such, it is most evident along high contrast edges in areas of generally smooth texture in the reconstruction, and appears as a shimmering or rippling outwards from the edge up to the encompassing block’s boundary
KC傅里叶变换及其变种的缺陷 Original (5.3 msec) 频域系数在编码过程 中的量化产生的量 误差在时域被扩展 了 ◆1807年傅里叶分析方法提出以来，傅里叶分析已成为信 号处理的主要工具之一，但是令人遗憾的是，在分析突变 信号和非平稳信号时，傅里叶分析却无能为力。 ◆1898年，Gibbs'paper ◆寻找新的正交展开系，使之能适应突变信号和非平稳信 号分析的需求成为研究热点之一。小波变换正是在这一背 景下产生的。 25 ynh.cxh @ustc.edu.cn
{ynh,cxh}@ustc.edu.cn 傅里叶变换及其变种的缺陷 1807年傅里叶分析方法提出以来，傅里叶分析已成为信 号处理的主要工具之一，但是令人遗憾的是，在分析突变 信号和非平稳信号时，傅里叶分析却无能为力。 1898年，Gibbs’ paper 寻找新的正交展开系，使之能适应突变信号和非平稳信 号分析的需求成为研究热点之一。小波变换正是在这一背 景下产生的。 25 频域系数在编码过程 中的量化产生的量化 误差在时域被扩展了