- From: Chris Lilley <chris@w3.org>
- Date: Thu, 29 Apr 2021 13:34:36 -0400
- To: public-colorweb@w3.org
On 2021-04-28 15:23, Christopher Cameron wrote: > In all browsers today, for "Colorbars in HLG 203 display.png", any > signal value above 0.75 is clamped to SDR-white. The choice of 0.75 follows from the HLG specification - a code value of 0.75 is media white, while a code value of 1.0 is peak white and is 12x higher luminance. The choice of clamping all HDR highlights, with no tone mapping is an easy but bad one. However, dislaying HDR content on SDR is in general hard; HLG is easier here than PQ (by design). > > Going back to the <img> tag situation, should 0.75 in this image > always match sRGB-white on HDR displays (even if sRGB-white is 80, > 100, or 400 nits)? Yes, it should.(80, 100, 140, 203, or 400 - 203 is the ITU value) Although media white increases typically mean brighter viewing conditions, which may require an OOTF to compensate for the decreased contrast. -- Chris Lilley @svgeesus Technical Director @ W3C W3C Strategy Team, Core Web Design W3C Architecture & Technology Team, Core Web & Media
Received on Thursday, 29 April 2021 17:34:38 UTC