LOCO-ANS: An Optimization of JPEG-LS Using an Efficient and Low-Complexity Coder Based on ANS
Entity
UAM. Departamento de Tecnología Electrónica y de las ComunicacionesPublisher
Institute of Electrical and Electronics Engineers Inc. (IEEE)Date
2021-07-27Citation
10.1109/ACCESS.2021.3100747
IEEE Access 9 (2021): 106606-106626
ISSN
2169-3536 (online)DOI
10.1109/ACCESS.2021.3100747Funded by
This work was supported in part by the Spanish Research Agency through the Project AgileMon under Grant AEI PID2019-104451RB-C21Project
Gobierno de España. AEI PID2019-104451RB-C21Editor's Version
https://doi.org/10.1109/ACCESS.2021.3100747Subjects
asymmetric numeral systems; Image codec; JPEG-LS; low complexity; near-lossless compression; two-sized geometric distribution; TelecomunicacionesRights
© The author(s)Abstract
Near-lossless compression is a generalization of lossless compression, where the codec user is able to set the maximum absolute difference (the error tolerance) between the values of an original pixel and the decoded one. This enables higher compression ratios, while still allowing the control of the bounds of the quantization errors in the space domain. This feature makes them attractive for applications where a high degree of certainty is required. The JPEG-LS lossless and near-lossless image compression standard combines a good compression ratio with a low computational complexity, which makes it very suitable for scenarios with strong restrictions, common in embedded systems. However, our analysis shows great coding efficiency improvement potential, especially for lower entropy distributions, more common in near-lossless. In this work, we propose enhancements to the JPEG-LS standard, aimed at improving its coding efficiency at a low computational overhead, particularly for hardware implementations. The main contribution is a low complexity and efficient coder, based on Tabled Asymmetric Numeral Systems (tANS), well suited for a wide range of entropy sources and with simple hardware implementation. This coder enables further optimizations, resulting in great compression ratio improvements. When targeting photographic images, the proposed system is capable of achieving, in mean, 1.6%, 6%, and 37.6% better compression for error tolerances of 0, 1, and 10, respectively. Additional improvements are achieved increasing the context size and image tiling, obtaining 2.3% lower bpp for lossless compression. Our results also show that our proposal compares favorably against state-of-the-art codecs like JPEG-XL and WebP, particularly in near-lossless, where it achieves higher compression ratios with a faster coding speed
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Google Scholar:Alonso, Tobias
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Sutter Capristo, Gustavo Daniel
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López de Vergara Méndez, Jorge Enrique
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