HDR and color management in KWin, part 5: HDR on SDR laptops

In Plasma 6.2, KWin switched from doing linear blending with HDR to blending in a gamma 2.2 space. Let’s take a look at what that means, and why it was done.

Fractional scaling is hard. Anyone that had the misfortune of working on it knows that… so it won’t surprise a lot of people that it’s not all figured out yet! Today I’ll talk about the fractional scaling problems with KWin’s server side decorations, and why we need to do an API break to fix it.

Profiling displays is already not a super simple thing on its own, but things get more complicated when you try to profile your display in Wayland - profiling applications don’t support Wayland yet, some APIs on the compositor side to make it work well are still missing, and there’s a general lack of information on the topic. So today I’ll show...

KWin had a very long standing bug report about bad performance of the Wayland session on older Intel integrated graphics. There have been many investigations into what’s causing this, with a lot of more specific performance issues being found and fixed, but none of them managed to fully fix the issue… until now.

Since the last two posts about this topic (part one, part two) there has been some more progress, so let’s take a look.