Cross-Color Channel Perceptually Adaptive Quantization for HEVC

TL;DR

This paper introduces a novel cross-color channel perceptually adaptive quantization method for HEVC that improves coding efficiency by adjusting quantization parameters based on combined spatial activity across luminance and chroma channels.

Contribution

The paper proposes a new cross-color channel adaptive quantization scheme that considers all three color channels for perceptual adjustment, enhancing HEVC coding efficiency.

Findings

Maximum BD-Rate reduction of 15.9% in Y channel

Maximum BD-Rate reduction of 13.1% in Cr channel

Maximum decoding time reduction of 11.0%

Abstract

HEVC includes a Coding Unit (CU) level luminance-based perceptual quantization technique known as AdaptiveQP. AdaptiveQP perceptually adjusts the Quantization Parameter (QP) at the CU level based on the spatial activity of raw input video data in a luma Coding Block (CB). In this paper, we propose a novel cross-color channel adaptive quantization scheme which perceptually adjusts the CU level QP according to the spatial activity of raw input video data in the constituent luma and chroma CBs; i.e., the combined spatial activity across all three color channels (the Y, Cb and Cr channels). Our technique is evaluated in HM 16 with 4:4:4, 4:2:2 and 4:2:0 YCbCr JCT-VC test sequences. Both subjective and objective visual quality evaluations are undertaken during which we compare our method with AdaptiveQP. Our technique achieves considerable coding efficiency improvements, with maximum BD-Rate reductions of 15.9% (Y), 13.1% (Cr) and 16.1% (Cb) in addition to a maximum decoding time reduction of 11.0%.