You can put crazy numbers in MaxFALL and MaxCLL and get exactly the same picture

“Unfortunately, for HDR10, there is no reference implementation, like everyone does its own kind of HDR10, so some TVs do clipping, some TVs do their own kind of tone mapping, and in fact, if you mess up with the static metadata, like MaxFALL and MaxCLL, nothing happens in the picture, so trust me, you can just, you know, put a crazy number in MaxFALL and MaxCLL and you get this exactly the same picture.” – Dr. Hojatollah Yeganeh, Principal Video Architect at SSIMWAVE Inc., speaking at Demuxed ‘22

Steven Robertson, software engineer at Google, has said basically the same thing – TVs all pretty much ignore or do their own thing with static metadata. As has Michael Zink, Vice President, Emerging & Creative Technologies at WarnerMedia, who, along with Michael D. Smith, authored “On the Calculation and Usage of HDR Static Content Metadata,” published in the SMPTE Motion Imaging Journal, Aug. 2021. As opposed to HDR10, HDR10+ and Dolby Vision both carry dynamic metadata and TVs do apply tone mapping, but different TMOs produce varying degrees of detail loss, either in the shadows, the highlights, or both. Another issue, not discussed in the video, is that tone mapping also increases noise in the shadows.

Photo: Dr. Hojatollah Yeganeh

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