Created attachment 179523 [details] YCBCR420 picture I'm using LG C2 TV as monitor with KDE Plasma 6.3 My Lenovo X1 carbon Gen9 laptop allows using it with 4K@120HZ over type C with cable matters typec->hdmi adapter. Half of time KDE connects to the monitor using RGB 8 bit , which is looking totally fine. But another half connects with YCBCR420 8bit , which provides bad rainbow effect and makes text unreadable. The fact it there is no consistency makes me puzzled that that color space selection is not really controlled. I checked on Windows 11, it consistenly using RGB 8bit, so problem is specific to Linux. Problem is reproduced only with 4K@120HZ, 4K@60HZ Consistently using RGB. Hardware: Lenovo X1 carbon Gen9 cable matters typec->hdmi 4k 120Hz adapter LG C2 42" as monitor Software: Debian 12 Testing Kde Plasma 6.3 Wayland (But also was present with 5.27) Qt 6.7.2 Kernel 6.12
Created attachment 179524 [details] RGB 8 bit picture
KWin doesn't decide the encoding, there is sadly no API to do that. Please report this to at https://gitlab.freedesktop.org/drm/intel/-/issues