High Dynamic Range Video Compression Exploiting Luminance Masking

Signal Processing: Image Communication

2018

warwick.ac.uk/lib-publicationsOriginal citation: Prangnell, Lee (2017) Visually lossless coding in HEVC : a high bit depth and 4:4:4 capable JND-based perceptual quantisation technique for HEVC. Permanent WRAP URL:http://wrap.warwick.ac.uk/91416 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work by researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. A note on versions:The version presented here is a working paper or pre-print that may be later published elsewhere. If a published version is known of, the above WRAP URL will contain details on finding it. Abstract -Due to the increasing prevalence of high bit depth and YCbCr 4:4:4 video data, it is desirable to develop a JND-based visually lossless coding technique which can account for high bit depth 4:4:4 data in addition to standard 8-bit precision chroma subsampled data. In this paper, we propose a Coding Block (CB)-level JND-based luma and chroma perceptual quantisation technique for HEVC named Pixel-PAQ. Pixel-PAQ exploits both luminance masking and chrominance masking to achieve JND-based visually lossless coding; the proposed method is compatible with high bit depth YCbCr 4:4:4 video data of any resolution. When applied to YCbCr 4:4:4 high bit depth video data, Pixel-PAQ can achieve vast bitrate reductions -of up to 75% (68.6% over four QP data points) -compared with a state-of-the-art luma-based JND method for HEVC named IDSQ. Moreover, the participants in the subjective evaluations confirm that visually lossless coding is successfully achieved by Pixel-PAQ (at a PSNR value of 28.04 dB in one test).

Section: Overview Of Related Workmentioning

confidence: 99%

Visually lossless coding in HEVC: A high bit depth and 4:4:4 capable JND-based perceptual quantisation technique for HEVC

Signal Processing: Image Communication

2018

“…where B and R refer to the normalized spatial activity of chroma Cb and Cr CBs, respectively. B and R are computed in (11) and (12), respectively: where m Cb and m Cr denote the number of pixel values in sub-blocks k and z, respectively (see Fig. 2), where v n and j n refer to the n th pixel values in sub-blocks k and z, respectively, and where μ Cb and μ Cr correspond to the mean pixel values of sub-blocks k and z, respectively.…”

Section: Proposed Fcpq Technique For Hevcmentioning

confidence: 99%

Coding block-level perceptual video coding for 4:4:4 data in HEVC

2017 IEEE International Conference on Image Processing (ICIP)

Hernández-Cabronero

Sánchez

2017

There is an increasing consumer demand for high bit-depth 4:4:4 HD video data playback due to its superior perceptual visual quality compared with standard 8-bit subsampled 4:2:0 video data. Due to vast file sizes and associated bitrates, it is desirable to compress raw high bit-depth 4:4:4 HD video sequences as much as possible without incurring a discernible decrease in visual quality. In this paper, we propose a Coding Block (CB)-level perceptual video coding technique for HEVC named Full Color Perceptual Quantization (FCPQ). FCPQ is designed to adjust the Quantization Parameter (QP) at the CB level -i.e., the luma CB and the chroma Cb and Cr CBs -according to the variances of pixel data in each CB. FCPQ is based on the default perceptual quantization method in HEVC called AdaptiveQP. AdaptiveQP adjusts the QP of an entire 2N×2N CU based only on the spatial activity of the constituent luma CB. As demonstrated in this paper, by not accounting for the spatial activity of the constituent chroma CBs, as is the case with AdaptiveQP, coding performance can be significantly affected; this is because the variance of pixel data in a luma CB is notably different from the variances of pixel data in chroma Cb and Cr CBs. FCPQ, therefore, addresses this problem. In terms of coding performance, FCPQ achieves BD-Rate improvements of up to 39.5% (Y), 16% (Cb) and 29.9% (Cr) compared with AdaptiveQP.

“…Therefore, in the HEVC standard the maximum QP permitted for chroma data is QP = 39 (chroma QP offset [14]) for YCbCr 4:2:0 chroma subsampled input video data [14]- [18]. Variables b and d are computed in (9) and (10)…”

Section: Proposed C-baq Technique For Hevcmentioning

confidence: 99%

Cross-Color Channel Perceptually Adaptive Quantization for HEVC

2017 Data Compression Conference (DCC)

Hernández-Cabronero

Sánchez

2017

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 the pixel 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 pixel 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%.