Colors over saturated in umbriel

written9676 commented

2026-10-08 15:20:23 +00:00

Hey there, I like the new umbriel feature of window selection, however it seems to have a regression with hdr. Specifically, when hdr = on in umbriel config, screenshot colors will be very over saturated. If hdr gets turned off everything is fine. In aqueous this is not a problem FWIW.

Hey there, I like the new umbriel feature of window selection, however it seems to have a regression with hdr. Specifically, when `hdr = on` in umbriel config, screenshot colors will be very over saturated. If hdr gets turned off everything is fine. In aqueous this is not a problem FWIW.

written9676 commented

2026-10-08 15:24:13 +00:00

Author

No description provided.

hdr-off.png

761 KiB

hdr-on.png

806 KiB

creations commented

2026-10-08 18:07:01 +00:00

Owner

when hdr is on, umbriel reports the output as pq / bt.2020, but the 10-bit
buffer it hands back from screencopy holds the same sdr-encoded pixels it
gives you with hdr off. grabit assumes the capture is in the output's
encoding, so it decodes those pixels as pq and maps them from bt.2020 to
srgb. that crushes the shadows and blows out the saturation.

i confirmed it by running your hdr-off.png through grabit's tonemap as if it
were pq/bt.2020. it matches your hdr-on.png to within rounding.

no protocol says what encoding a capture buffer is in, so neither side is
breaking a rule here. hyprland hands pq to clients that bind the color
manager and srgb to everyone else, and wlroots copies the scanout buffer,
so grabit's assumption holds there. umbriel always hands back sdr.

either umbriel follows hyprland's convention for color-managed clients, or
grabit stops making that assumption on umbriel.

when hdr is on, umbriel reports the output as pq / bt.2020, but the 10-bit buffer it hands back from screencopy holds the same sdr-encoded pixels it gives you with hdr off. grabit assumes the capture is in the output's encoding, so it decodes those pixels as pq and maps them from bt.2020 to srgb. that crushes the shadows and blows out the saturation. i confirmed it by running your hdr-off.png through grabit's tonemap as if it were pq/bt.2020. it matches your hdr-on.png to within rounding. no protocol says what encoding a capture buffer is in, so neither side is breaking a rule here. hyprland hands pq to clients that bind the color manager and srgb to everyone else, and wlroots copies the scanout buffer, so grabit's assumption holds there. umbriel always hands back sdr. either umbriel follows hyprland's convention for color-managed clients, or grabit stops making that assumption on umbriel.

written9676 commented

2026-10-09 02:11:08 +00:00

Author

So would this be something I bring to the umbriel devs to think about then?

written9676 commented

2026-10-09 14:03:43 +00:00

Author

I talked to one of their devs and they pushed a fix. So, sorry for opening this here!

written9676 closed this issue

2026-10-09 14:03:43 +00:00

Rows
Columns

Colors over saturated in umbriel #9