- From: Chris Lilley via GitHub <sysbot+gh@w3.org>
- Date: Thu, 17 Apr 2025 18:43:13 +0000
- To: public-css-archive@w3.org
Calculating that sort of luminance histogram analysis on the fly can be expensive, so it is typically pre-computed and stored as static metadata in the image, animation or video. This is how [HDR10](https://en.wikipedia.org/wiki/HDR10) does it; the relevant items are - MaxFALL (maximum frame-average light level) - MaxCLL (maximum content light level) PNG recently added this capability, in the [Content Light Level (`cLLI`) chunk](https://w3c.github.io/png/#cLLI-chunk). AVIF [also supports HDR10 static metadata and HDR10+ dynamic metadata](https://aomediacodec.github.io/av1-hdr10plus/) The definition of MaxFALL and MaxCLL is in [CTA-861.3-A](https://shop.cta.tech/products/cta-861-3) and the method of calculation used in practice is described in [On the Calculation and Usage of HDR Static Content Metadata](https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=9508136). Smith, Michael D.; Zink, Michael. Society of Motion Picture and Television Engineers. 2021-08-05. None of these specifications say **how** to use that information, so that is where CSS Color HDR could provide guidance. -- GitHub Notification of comment by svgeesus Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/12096#issuecomment-2813759061 using your GitHub account -- Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config
Received on Thursday, 17 April 2025 18:43:14 UTC