Lossless Intra Coding in HEVC with 3-tap Filters
This work addresses video compression efficiency for HEVC users, representing an incremental improvement over existing methods.
The paper tackles the problem of improving lossless intra coding in HEVC by proposing a pixel-by-pixel spatial prediction method using 3-tap filters, which achieves an average 11.34% bitrate reduction and decreases decoding time by 12.7% while increasing encoding time by 9.7%.
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%