文献类型：期刊文献

英文题名：An Ultra-Low Complexity and High Efficiency Approach for Lossless Alpha Channel Coding

作者：Zhao, Liping[1];Lin, Tao[2];Zhang, Dongyu[2];Zhou, Kailun[2];Wang, Shuhui[2]

机构：[1]Shaoxing Univ, Dept Comp Sci & Engn, Shaoxing 312000, Peoples R China;[2]Tongji Univ, Inst VLSI, Coll Elect & Informat Engn, Shanghai 200092, Peoples R China

年份：2020

卷号：22

期号：3

起止页码：786

外文期刊名：IEEE TRANSACTIONS ON MULTIMEDIA

收录：SCI-EXPANDED(收录号：WOS:000519576700017)、、EI(收录号：20201008266089)、Scopus(收录号：2-s2.0-85080861986)、WOS

基金：This work was supported in part by the Natural Science Foundation of Zhejiang Province (LY19F020015), in part by the National Natural Science Foundation of China under Grants 61871289 and 61601200, in part by the Public Service Technology ApplicationResearch Project of Shaoxing city (2018C10015), and in part by the Natural Science Foundation of Shanghai Province (18ZR1440600, 19ZR1461100).

语种：英文

外文关键词：Complexity theory; Channel coding; Image coding; Standards; Video coding; Unified modeling language; Image coding; alpha channel coding; string matching; prediction coding; variable length code

外文摘要：Alpha channel is being applied in an increasing number of mobile web applications on mobile devices that require ultra-low power consumption in all cases including compute-intensive video encoding and decoding. Thus, we propose an ultra-low coding complexity and high efficiency alpha channel lossless coding approach. A novel coding framework and four new coding schemes are proposed for alpha channel coding. The framework fuses a string matching technique and a proposed prediction coding scheme named bit-depth preserving prediction (BDPP) together to reduce the correlations within and between repeated identical patterns and neighboring pixels. To achieve a good tradeoff between complexity and efficiency, either the unmatchable bytes are coded directly or the BDPP residuals of unmatchable bytes are coded by a proposed bytewise entropy coding scheme named 0.5-1-2byte-size-code. The other string matching parameters are coded by another proposed bytewise entropy coding scheme named byte-size multi-variable-length-code. To speed up the string-matching search, we apply a fast string search scheme that combines special position search and hash-based search. For the selected typical 236 alpha test images, compared with x265 in the fastest configuration and lossless mode, the proposed lossless approach achieves 14.33% less total compressed bytes with only 2.75% encoding and 1.83% decoding runtime. The proposed approach also outperforms the conventional lossless coding techniques such as LZ4HC, ZLIB, and PNG.