Lossless Intra Coding in HEVC with 3-tap Filters

TL;DR

This paper introduces a 3-tap pixel prediction method for lossless intra coding in HEVC, achieving significant bitrate reduction and faster decoding, with a slight increase in encoding time.

Contribution

It proposes a novel 3-tap filtering prediction method for lossless HEVC intra coding, improving compression efficiency and decoding speed over existing methods.

Findings

11.34% average bitrate reduction

12.7% faster decoding time

9.7% increased encoding time

Abstract

This paper presents a pixel-by-pixel spatial prediction method for lossless intra coding within High Efficiency Video Coding (HEVC). A well-known previous pixel-by-pixel spatial prediction method uses only two neighboring pixels for prediction, based on the angular projection idea borrowed from block-based intra prediction in lossy coding. This paper explores a method which uses three neighboring pixels for prediction according to a two-dimensional correlation model, and the used neighbor pixels and prediction weights change depending on intra mode. To find the best prediction weights for each intra mode, a two-stage offline optimization algorithm is used and a number of implementation aspects are discussed to simplify the proposed prediction method. The proposed method is implemented in the HEVC reference software and experimental results show that the explored 3-tap filtering method can achieve an average 11.34% bitrate reduction over the default lossless intra coding in HEVC. The proposed method also decreases average decoding time by 12.7% while it increases average encoding time by 9.7%