Wayland color management

[Dmitry_Kazakov]

@gwgill

0. Display color space can be: sRGB-like, AdobeRGB-like, p2020-pq. First two can be defined by an ICC, the last one should use so special treatment.

In general displays aren’t “like” any particular colorspace - they are what they measure to be. i.e. if they are color managed, they are always defined by a profile.

Yes, “sRGB-like” was just a short name for “a color space with primaries and EOTF something like in sRGB”

The point I wanted to tell was unrelated though: as far as I know, it is impossible to describe an HDR color space with an ICC profile. Though it needs some investigation.

@gwgill

1. The entire window is painted on an sRGB-8bit surface that is converted by the compositor into the color space of the display.

[…]
Perhaps you meant that you would like a default conversion that assumes sRGB source space for non color aware applications or the GUI elements that you render ?

Yes, exactly. GUI elements, like menus and buttons, are expected to be painted on sRGB surface, but the canvas with actual image data is expected to be painted on a separate surface with a different color tag.

@gwgill

2. In the middle of the window there is an overlay pass-though surface for the canvas. This canvas is explicitly color-corrected into the display color space by Krita itself. Compositor just passes it through to the display.

Why should it be special ? Shouldn’t there be any number of color managed applications and windows displayed on a screen at once ?

I mean the app should have two surfaces: one with sRGB tag for GUI elements (for which the compositor does color management) and the other one for actual image data (compositor passes it directly to the display).

@gwgill

1. We create an 8-bit sRGB surface for the entire window. Basically, it disables any so-called “color management” from Windows’ side.

I’m not clear on what you mean by that. You are using a color managed API and then using the null profile trick to disable color management for MSWindows ?

There is not color management for DXGI surfaces in Windows, even though MS claims there is. You create an sRGB surface, and DirectX passes the data directly to GPU without any conversions. Calling SetICMMode for the corresponding HDC doesn’t do anything.