On Thu, Mar 7, 2019 at 2:35 PM Graeme Gill <grae...@argyllcms.com> wrote: > > Michel Dänzer wrote: > > > It sounds like KMS leases could be a pretty good fit for a calibration > > application. It can lease each output individually from the Wayland > > compositor and fully control it using KMS APIs, while the Wayland > > compositor continues running normally on other outputs. > > There seems to be this idea that has got a hold amongst many commentators > on this topic here, that somehow the display calibration and profiling > application NEEDs raw and direct access to the a display to operate.
Just to underscore how mistaken such an assumption would be, the self-calibrating displays on the market produce a display state of behavior (white point, black point, primaries, and tone reproduction curve), and an ICC profile that describes that state, without any respect whatsoever to behaviors in the OS or the connection between display and computer. That ICC profile correctly describes that display whether the OS is macOS or Windows. If everything is correctly done, that would also be true for Linux whether GNOME, KDE, Xorg, or any Wayland compositor. The profile doesn't describe how wrong a display is, it doesn't describe a correction. It merely maps RGB values, submitted by an ordinary application for display, to their color appearance (all kinds of media, environment, observer assumptions are baked into that term). The small problem we might have for the rest of the displays that aren't self-calibrating, is lack of platform support parity for the various video card LUTs. But for that (important) detail, it should otherwise be true that an ICC profile describes the display's state regardless of the display rendering pipeline (ergo, regardless of platform). -- Chris Murphy _______________________________________________ wayland-devel mailing list wayland-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/wayland-devel