Various earlier work in MPEG/JCTVC have shown that out-loop reshaping, which modifies the video signal in preprocessing before encoding and post-processing after decoding in an end-to-end video compression workflow, can improve subjective quality of coded High Dynamic Range (HDR) and Wider Color Gamut (WCG) content compressed using HEVC. However, the requirement of not making normative changes to the HEVC specification has significantly constrain the design and optimization of the reshaper. In April 2018, The Joint Video Experts Team (JVET) has launched a project to develop a new video coding standard to be known as Versatile Video Coding (VVC). This opens the door to exploit possibilities of the reshaper design inside of the core video codec. In this paper, an in-loop architect of reshaper is presented. Preliminary results suggest that the in-loop reshaping architect can retain the functionality of out-loop reshaper. In addition, the in-loop design can resolve many limitations of the out-loop design and can be used as a general coding tool for general video content not limited to HDR.
High Dynamic Range (HDR) and Wider Color Gamut (WCG) content represents a greater range of luminance levels and
a more complete reproduction of colors found in real-world scenes. The characteristics of HDR/WCG content are very
different from the SDR content. It poses a challenge to the compression system which is originally designed for SDR
content. Recently in MPEG/VCEG, two directions have been taken to improve compression performances for
HDR/WCG video using HEVC Main10 codec. The first direction is to improve HDR-10 using encoder optimization.
The second direction is to modify the video signal in pre/post processing to better fit compression system. The process
therefore is out of coding loop and does not involve changes to the HEVC specification. Among many proposals in the
second direction, reshaper is identified to be the key component. In this paper, a novel luma reshaper is presented which
re-allocates the codewords to help codec improve subjective quality. In addition, encoder optimization can be performed
jointly with reshaping. Experiments are conducted with ICtCp color difference signal. Simulation results show that if
both joint optimization of reshaper and encoder are carried out, there is evidence that improvement over the HDR-10
anchor can be achieved.
Proc. SPIE. 9599, Applications of Digital Image Processing XXXVIII
KEYWORDS: Visual process modeling, Video, Computer programming, Colorimetry, Signal processing, Video compression, High dynamic range imaging, Human vision and color perception, Video coding, RGB color model
High Dynamic Range (HDR) and Wider Color Gamut (WCG) content represents a greater range of luminance levels and a more complete reproduction of colors found in real-world scenes. The current video distribution environments deliver Standard Dynamic Range (SDR) signal. Therefore, there might be some significant implication on today's end-to-end ecosystem from content creation to distribution and finally to consumption. For SDR content, the common practice is to apply compression on Y'CbCr 4:2:0 using gamma transfer function and non-constant luminance 4:2:0 chroma subsampling. For HDR and WCG content, it is desirable to examine if such signal format still works well for compression, and it is interesting to know if the overall system performance can be further improved by exploring different signal formats and processing workflows. In this paper, we will provide some of our insight into those problems.
3D content is gaining popularity and the production and delivery of 3D video is now an active working item among
video compression experts, content providers and the CE industry. Frame compatible stereo coding was initially adopted
for the first generation of 3DTV broadcasting services for its compatibility with existing 2D decoders. However, the
frame compatible solution sacrifices half of the original video resolution. In 2012, the Moving Picture Experts Group
(MPEG) issued the call for proposal (CfP) for solutions that improve the resolution of frame compatible stereo 3D video
signal while maintaining the backward compatibility to legacy decoders. The standardization process of the multiresolution
frame compatible (MFC) stereo coding was then started. In this paper, the solution – Orthogonal Muxing
Frame Compatible Full Resolution (OM-FCFR) – as a response to the CfP is introduced. In addition, this paper provides
some experimental results for broadcasters to guide them in selecting operating points for MFC. It is observed that for
typical broadcast bitrates, more than 0.5dB PSNR improvement can be achieved by MFC over the frame compatible
solution with only 15%~20% overhead.