Graphics Reference
In-Depth Information
Chapter 7
In-Loop Filters in HEVC
Andrey Norkin, Chih-Ming Fu, Yu-Wen Huang, and Shawmin Lei
Abstract The HEVC standard specifies two in-loop filters, a deblocking filter and
a sample adaptive offset (SAO). The in-loop filters are applied in the encoding
and decoding loops, after the inverse quantization and before saving the picture
in the decoded picture buffer. The deblocking filter is applied first. It attenuates
discontinuities at the prediction and transform block boundaries. The second in-loop
filter, SAO, is applied to the output of the deblocking filter and further improves the
quality of the decoded picture by attenuating ringing artifacts and changes in sample
intensity of some areas of a picture. The most important advantage of the in-loop
filters is improved subjective quality of reconstructed pictures. In addition, using the
filters in the decoding loop also increases the quality of the reference pictures and
hence also the compression efficiency.
7.1
Introduction
The in-loop filters constitute an important part of the HEVC video coding standard.
As seen from the name, the in-loop filters are applied in the encoding and decoding
loops, after the inverse quantization but before saving the picture to the decoded
picture buffer. HEVC standard specifies two in-loop filters, a deblocking filter,
which is applied first, and a sample adaptive offset (SAO), which is applied to the
output of the [ 40 ] deblocking filter. The deblocking filter attenuates discontinuities
at prediction and transform block boundaries [ 36 , 37 ]. The SAO further improves
A. Norkin ( )
Ericsson Research, Ericsson, Stockholm, Sweden
e-mail: andrey.norkin@ericsson.com
C.-M. Fu ￿ Y.-W. Huang ￿ S. Lei
MediaTek, Hsinchu, Taiwan
e-mail: chihming.fu@mediatek.com ; yuwen.huang@mediatek.com ; shawmin.lei@mediatek.com
Search WWH ::




Custom Search