High throughput hardware architectures for asymmetric numeral systems entropy coding

Najmabadi, Seyyed Mahdi; Wang, Zhe; Baroud, Yousef; Simon, Sven

doi:10.1109/ispa.2015.7306068

Cited by 15 publications

(17 citation statements)

References 8 publications

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“…• Has high-throughput implementations. For Field Programmable Gate Arrays (FPGA), encoder architectures were studied in [30] and decoder in [31], which can outperform Huffman decoding [32].…”

Section: B Asymmetric Numeral Systemsmentioning

confidence: 99%

“…For more in depth explanation of the ANS algorithm and hardware implementations, refer to [18], [30], [31].…”

Section: ) Tans Operationmentioning

confidence: 99%

“…Increasing precision comes at the cost of increasing memory requirements for the FSM ROM. However, the impact of this increment depends on the actual implementation and, as shown in [30], efficient architectures exist for large state configurations.…”

Section: ) Coding Efficiencymentioning

confidence: 99%

“…Each element of the table is a structure with the number of bits that should be sent to the output and the next ANS state. Note that ANS operation can be implemented differently [19], [30].…”

Section: ) Subsymbol Codification Ordermentioning

confidence: 99%

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LOCO-ANS: An Optimization of JPEG-LS Using an Efficient and Low-Complexity Coder Based on ANS

2021

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Near-lossless compression is a generalization of lossless 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 to control 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 a 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.

show abstract

Section: B Asymmetric Numeral Systemsmentioning

confidence: 99%

“…For more in depth explanation of the ANS algorithm and hardware implementations, refer to [18], [30], [31].…”

Section: ) Tans Operationmentioning

confidence: 99%

Section: ) Coding Efficiencymentioning

confidence: 99%

Section: ) Subsymbol Codification Ordermentioning

confidence: 99%

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LOCO-ANS: An Optimization of JPEG-LS Using an Efficient and Low-Complexity Coder Based on ANS

2021

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“…In this manuscript, we study Tabled ANS (tANS), which is an ANS variant that is well suited for hardware implementations [31], [32], [33]. It employs a finite state machine that transitions from state to state as symbols are encoded, which is certainly not a new idea [34].…”

Section: Introductionmentioning

confidence: 99%

Redundancy and Optimization of tANS Entropy Encoders

Blanes¹,

Hernández-Cabronero²,

Serra-Sagristà³

et al. 2021

IEEE Trans. Multimedia

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Nowadays entropy encoders are part of almost all data compression methods, with the Asymmetrical Numeral Systems (ANS) family of entropy encoders having recently risen in popularity. Entropy encoders based on the tabled variant of ANS are known to provide varying performances depending on their internal design. In this paper, we present a method that calculates encoder redundancies in almost linear time, which translates in practice to thousand-fold speedups in redundancy calculations for small automatons, and allows redundancy calculations for automatons with tens of millions of states that would be otherwise prohibitive. We also address the problem of improving tabled ANS encoder designs, by employing the aforementioned redundancy calculation method in conjunction with a stochastic hill climbing strategy. The proposed approach consistently outperforms state-of-the-art methods in tabled ANS encoder design. For automatons of twice the alphabet size, experimental results show redundancy reductions around 10% over the default initialization method and over 30% for random initialization.

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A simplified variant of tabled asymmetric numeral systems with a smaller look-up table

Wang

Lin

2020

Distrib Parallel Databases

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High throughput hardware architectures for asymmetric numeral systems entropy coding

Cited by 15 publications

References 8 publications

LOCO-ANS: An Optimization of JPEG-LS Using an Efficient and Low-Complexity Coder Based on ANS

LOCO-ANS: An Optimization of JPEG-LS Using an Efficient and Low-Complexity Coder Based on ANS

Redundancy and Optimization of tANS Entropy Encoders

A simplified variant of tabled asymmetric numeral systems with a smaller look-up table

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