Composing GUI elements into HDR canvas

[dimula73]

In his talk Timo Kunkel talked about compositing SDR content into HDR canvas. I would like to raise a broader discussion about the problem of composing GUI elements around the HDR content.

Here is Krita we allow painting of HDR images right inside the app. At the same time, the user should be able to access the GUI elements, which are, obviously, SDR. We use quite dumb approach and just render sRGB-based GUI by mapping its white point into 80 cd/m2 point of the HDR canvas. That somewhat works, but makes the GUI look dull, as soon as the user paint any HDR content on the canvas.

Are there any "good practices" for rendering GUI around HDR content? Perhaps we should dynamically adapt it somehow? Or we should solve the problem by some UIX solutions, like add a scrollbar for the user to change the brightness of the GUI on-the fly?

Some additional consideration:

• Windows has an system-wide option for GUI brightness. But it has two flaws: 1) it is not available to apps through any non-dot-net-API (at least I haven't found it); 2) It changes brightness of all the apps.

[therahedwig]

BT 2390-8 discusses compositing SDR into HDR in sections 10.1.1 10.1.2 and 10.2.1, I seem to recall that the w3c has a video-captions working group that has been discussing how to properly compose captions into the GUI, though I have no links.