HDR Production - Tone Mapping Techniques and Round-Trip Conversion Performance for Mastering with SDR and HDR Sources

• Published in: SMPTE 2022 Media Technology Summit pp. 1 - 21
• Main Authors: Touze, David, Plissonneau, Frederic, Redmann, Bill, Naour, Robin Le, Lopez, Patrick, Morvan, Patrick, Cauvin, Laurent, Mitchell, Nick, Stein, Alan
• Format: Conference Proceeding
• Language: English
• Published: SMPTE 01-10-2022
• Subjects: 3D-LUT; Diffuse White; HDR; HDR live production; Inverse Tone Mapping; ITM; round trip; SDR; Tone compression; Tone expansion; Tone Mapping
• ISBN: 1614829632; 9781614829638
• DOI: 10.5594/M001974

Where content producers had to make drastic choices when allocating the limited contrast and colors in SDR, HDR offers them the possibility to show more - meaning telling stories with greater freedom and flexibility. - However, while future-proof, HDR content presents a challenge of its own: The wide variation in capabilities among HDR displays conflicts with the desire to have any HDR or SDR production play optimally on any display, HDR or SDR, regardless. - The general solution to this issue is tone mapping, either tone compression, which maps from HDR to a lower-luminance HDR or SDR, or tone expansion, which maps from SDR or HDR to a higher-luminance HDR. - Though the trend is to produce the highest quality content in HDR, legacy content is ever-present, and lots of new content is still produced in SDR. Mixing feeds in production requires tone expansion for SDR content to match the HDR. Distribution paths can then require tone compression back to SDR without degradation. In this context, a perfect SDR - HDR - SDR round-trip conversion is required to preserve artistic intent for all content. Further, in a live context, such tools need to be automatic and low latency. - This paper discusses various tone mapping techniques, including static solutions such as look-up tables and dynamic solutions based on metadata. The relative advantages are considered and performance of each is analyzed. Particular attention is paid to the round-trip performance, which is important to content producers mastering both SDR and HDR sources yet wanting to exploit the full range of storytelling capabilities an HDR stream can offer.