An Improved SAO Scheme for Screen Content Coding

Mengmeng ZHANG  Chuan ZHOU  Jizheng XU  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E99-A   No.7   pp.1499-1502
Publication Date: 2016/07/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E99.A.1499
Type of Manuscript: LETTER
Category: Image
high efficiency video coding (HEVC),  sample adaptive offset,  deblocking filter,  screen content coding,  

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The High efficiency video coding (HEVC) standard defines two in-loop filters to improve the objective and subjective quality of the reconstructed frames. Through analyzing the effectiveness of the in-loop filters, it is noted that band offset (BO) process achieves much more coding gains for text region which mostly employ intra block copy (IntraBC) prediction mode. The intraBC prediction process in HEVC is performed by using the already reconstructed region for block matching, which is similar to motion compensation. If BO process is applied after one coding tree unit (CTU) encoded, the distortion between original and reconstructed samples copied by the IntraBC prediction will be further reduced, which is simple to operate and can obtain good coding efficiency. Experimental results show that the proposed scheme achieves up to 3.4% BD-rate reduction in All-intra (AI) for screen content sequences with encoding and decoding time no increase.