Bug 514768 - Banding artifacts in dark areas of videos
Summary: Banding artifacts in dark areas of videos
Status: RESOLVED INTENTIONAL
Alias: None
Product: kwin
Classification: Plasma
Component: colour-management (other bugs)
Version First Reported In: 6.5.5
Platform: CachyOS Linux
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2026-01-17 22:12 UTC by tails_lol
Modified: 2026-01-21 21:36 UTC (History)
5 users (show)

See Also:
Latest Commit:
Version Fixed/Implemented In:
Sentry Crash Report:


Attachments
picture of the banding (1.74 MB, image/jpeg)
2026-01-19 17:50 UTC, tails_lol
Details
full image but less contrast (1.99 MB, image/jpeg)
2026-01-19 17:51 UTC, tails_lol
Details
here the same area with the icc fix loaded (2.25 MB, image/jpeg)
2026-01-19 17:59 UTC, tails_lol
Details

Note You need to log in before you can comment on or make changes to this bug.
Description tails_lol 2026-01-17 22:12:06 UTC
***
If you're not sure this is actually a bug, instead post about it at https://discuss.kde.org

If you're reporting a crash, attach a backtrace with debug symbols; see https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports

Please remove this comment after reading and before submitting - thanks!
***

SUMMARY

when I use kde default icc profile (when none is selected)

I have very blocky blacks in video playback.

the fix is generally to load the official srgb default icc profile you can download from the internet.

the issue is, when using hdr you can’t use icc profiles anymore

and the blocky black video playback issue come back.

any fixes planed?

fixed icc profiles used :

https://registry.color.org/rgb-registry/srgbprofiles

OBSERVED RESULT


EXPECTED RESULT


SOFTWARE/OS VERSIONS
Windows: 
macOS: 
(available in the Info Center app, or by running `kinfo` in a terminal window)
Linux/KDE Plasma: 
KDE Plasma Version: 6.5.5
KDE Frameworks Version: 
Qt Version: 6

ADDITIONAL INFORMATION
Comment 1 Zamundaaa 2026-01-19 13:21:00 UTC
> the fix is generally to load the official srgb default icc profile you can
> download from the internet.
"sRGB" ICC profiles don't actually describe sRGB screens (as dumb as that sounds). What "sRGB" ICC profiles effectively do is reduce the brightness of dark colors.
There's a good chance the blocky blacks are just color banding that is present in many videos, and the "sRGB" ICC profile ends up hiding it. Or your screen is a bit different from a 'correct' sRGB screen, there's a few possibilities for how this could happen.

Please provide
- some example video in which you see the issue
- a photo of the problem on your screen (take it with your phone), so we're on the same page about what the problem looks like exactly
- the output of kscreen-doctor -o
- the EDID of your screen. You can find it in the info center app. Just copy it to a file and attach it here
Comment 2 tails_lol 2026-01-19 17:32:18 UTC
(In reply to Zamundaaa from comment #1)
> > the fix is generally to load the official srgb default icc profile you can
> > download from the internet.
> "sRGB" ICC profiles don't actually describe sRGB screens (as dumb as that
> sounds). What "sRGB" ICC profiles effectively do is reduce the brightness of
> dark colors.
> There's a good chance the blocky blacks are just color banding that is
> present in many videos, and the "sRGB" ICC profile ends up hiding it. Or
> your screen is a bit different from a 'correct' sRGB screen, there's a few
> possibilities for how this could happen.
> 
> Please provide
> - some example video in which you see the issue
> - a photo of the problem on your screen (take it with your phone), so we're
> on the same page about what the problem looks like exactly
> - the output of kscreen-doctor -o
> - the EDID of your screen. You can find it in the info center app. Just copy
> it to a file and attach it here

yes the problem is color banding. pure blacks make very dark blob or glitches on the screen and you are right the icc profile make blacks less noticeable from other colors.
i have the issue in 2 different screens , a dell s3222dgm and a samsung 7 series -43- -UE43TU7025KXXC HDR
note: the problem is not present on windows or on android boxes.

here the edid

# card1-DP-3 #######################
Block 0, Base EDID:
  EDID Structure Version & Revision: 1.4
  Vendor & Product Identification:
    Manufacturer: DEL
    Model: 53519
    Serial Number: 810310230 (0x304c5a56)
    Made in: week 23 of 2021
  Basic Display Parameters & Features:
    Digital display
    Bits per primary color channel: 8
    DisplayPort interface
    Maximum image size: 70 cm x 40 cm
    Gamma: 2.20
    DPMS levels: Standby Suspend Off
    Supported color formats: RGB 4:4:4, YCrCb 4:4:4, YCrCb 4:2:2
    First detailed timing includes the native pixel format and preferred refresh rate
    Display supports continuous frequencies
  Color Characteristics:
    Red  : 0.6601, 0.3261
    Green: 0.2656, 0.5791
    Blue : 0.1376, 0.1123
    White: 0.3017, 0.3535
  Established Timings I & II:
    IBM     :   720x400    70.081663 Hz   9:5     31.467 kHz     28.320000 MHz
    DMT 0x04:   640x480    59.940476 Hz   4:3     31.469 kHz     25.175000 MHz
    DMT 0x06:   640x480    75.000000 Hz   4:3     37.500 kHz     31.500000 MHz
    DMT 0x09:   800x600    60.316541 Hz   4:3     37.879 kHz     40.000000 MHz
    DMT 0x0b:   800x600    75.000000 Hz   4:3     46.875 kHz     49.500000 MHz
    DMT 0x10:  1024x768    60.003840 Hz   4:3     48.363 kHz     65.000000 MHz
    DMT 0x12:  1024x768    75.028582 Hz   4:3     60.023 kHz     78.750000 MHz
    DMT 0x24:  1280x1024   75.024675 Hz   5:4     79.976 kHz    135.000000 MHz
  Standard Timings:
    DMT 0x53:  1600x900    60.000000 Hz  16:9     60.000 kHz    108.000000 MHz (RB)
    DMT 0x3a:  1680x1050   59.954250 Hz  16:10    65.290 kHz    146.250000 MHz
    DMT 0x45:  1920x1200   59.884600 Hz  16:10    74.556 kHz    193.250000 MHz
    DMT 0x15:  1152x864    75.000000 Hz   4:3     67.500 kHz    108.000000 MHz
    DMT 0x33:  1600x1200   60.000000 Hz   4:3     75.000 kHz    162.000000 MHz
    DMT 0x23:  1280x1024   60.019740 Hz   5:4     63.981 kHz    108.000000 MHz
    DMT 0x52:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz
  Detailed Timing Descriptors:
    DTD 1:  2560x1440   59.950550 Hz  16:9     88.787 kHz    241.500000 MHz (697 mm x 392 mm)
                 Hfront   48 Hsync  32 Hback   80 Hpol P
                 Vfront    3 Vsync   5 Vback   33 Vpol N
    Display Product Serial Number: '4RTJT63'
    Display Product Name: 'DELL S3222DGM'
    Display Range Limits:
      Monitor ranges (Range Limits Only): 48-165 Hz V, 250-250 kHz H, max dotclock 650 MHz
  Extension blocks: 1
Checksum: 0x76

----------------

Block 1, CTA-861 Extension Block:
  Revision: 3
  Underscans IT Video Formats by default
  Basic audio support
  Supports YCbCr 4:4:4
  Supports YCbCr 4:2:2
  Native detailed modes: 1
  Video Data Block:
    VIC  16:  1920x1080   60.000000 Hz  16:9     67.500 kHz    148.500000 MHz (native)
    VIC   4:  1280x720    60.000000 Hz  16:9     45.000 kHz     74.250000 MHz
    VIC   3:   720x480    59.940060 Hz  16:9     31.469 kHz     27.000000 MHz
    VIC   2:   720x480    59.940060 Hz   4:3     31.469 kHz     27.000000 MHz
    VIC   1:   640x480    59.940476 Hz   4:3     31.469 kHz     25.175000 MHz
    VIC  17:   720x576    50.000000 Hz   4:3     31.250 kHz     27.000000 MHz
    VIC  19:  1280x720    50.000000 Hz  16:9     37.500 kHz     74.250000 MHz
    VIC  31:  1920x1080   50.000000 Hz  16:9     56.250 kHz    148.500000 MHz
    VIC  63:  1920x1080  120.000000 Hz  16:9    135.000 kHz    297.000000 MHz
  Audio Data Block:
    Linear PCM:
      Max channels: 2
      Supported sample rates (kHz): 48 44.1 32
      Supported sample sizes (bits): 24 20 16
  Speaker Allocation Data Block:
    FL/FR - Front Left/Right
  Detailed Timing Descriptors:
    DTD 2:  1920x1080  143.855701 Hz  16:9    162.269 kHz    337.520000 MHz (697 mm x 392 mm)
                 Hfront   48 Hsync  32 Hback   80 Hpol P
                 Vfront    3 Vsync   5 Vback   40 Vpol N
    DTD 3:  1920x1080  164.997447 Hz  16:9    186.447 kHz    387.810000 MHz (697 mm x 392 mm)
                 Hfront   48 Hsync  32 Hback   80 Hpol P
                 Vfront    3 Vsync  10 Vback   37 Vpol N
    DTD 4:  2560x1440  119.997589 Hz  16:9    182.996 kHz    497.750000 MHz (697 mm x 392 mm)
                 Hfront   48 Hsync  32 Hback   80 Hpol P
                 Vfront    3 Vsync   5 Vback   77 Vpol N
    DTD 5:  2560x1440  143.911545 Hz  16:9    222.056 kHz    592.000000 MHz (697 mm x 392 mm)
                 Hfront    8 Hsync  32 Hback   66 Hpol P
                 Vfront   25 Vsync   8 Vback   70 Vpol N
    DTD 6:  2560x1440  165.079853 Hz  16:9    244.318 kHz    645.000000 MHz (697 mm x 392 mm)
                 Hfront    8 Hsync  32 Hback   40 Hpol P
                 Vfront    6 Vsync   8 Vback   26 Vpol N
Checksum: 0xfa

----------------

EDID conformity: PASS
Comment 3 tails_lol 2026-01-19 17:37:44 UTC
video showing the glitch
https://www.youtube.com/watch?v=s4FnAOg6N5c
Comment 4 tails_lol 2026-01-19 17:50:32 UTC
Created attachment 188688 [details]
picture of the banding
Comment 5 tails_lol 2026-01-19 17:51:38 UTC
Created attachment 188689 [details]
full image but less contrast
Comment 6 tails_lol 2026-01-19 17:59:41 UTC
Created attachment 188690 [details]
here the same area with the icc fix loaded

I joined an image with the icc fix loaded.
Comment 7 Zamundaaa 2026-01-19 19:18:28 UTC
Okay, so the banding is there either way, on your screen it's just less noticeable with the ICC profile applied. On mine it looks a tad worse with the ICC profile, it'll depends a lot on the screen.

The default color profile matches a correct sRGB screen, and ends up just copying sRGB window contents to the screen, without any modification. I don't think changing that would be a good idea.
The EDID also doesn't contain any additional information we could use to change the default to match it better, it claims to follow the gamma 2.2 transfer function.

What app are you using to play the video?

With
> samsung 7 series -43- -UE43TU7025KXXC HDR
did you mean that you also had HDR enabled in Plasma on that screen?
Comment 8 tails_lol 2026-01-20 05:39:28 UTC
(In reply to Zamundaaa from comment #7)
> Okay, so the banding is there either way, on your screen it's just less
> noticeable with the ICC profile applied. On mine it looks a tad worse with
> the ICC profile, it'll depends a lot on the screen.
> 
> The default color profile matches a correct sRGB screen, and ends up just
> copying sRGB window contents to the screen, without any modification. I
> don't think changing that would be a good idea.
> The EDID also doesn't contain any additional information we could use to
> change the default to match it better, it claims to follow the gamma 2.2
> transfer function.
> 
> What app are you using to play the video?
> 
> With
> > samsung 7 series -43- -UE43TU7025KXXC HDR
> did you mean that you also had HDR enabled in Plasma on that screen?

Using mostly chrome and Firefox since I watch mostly streaming online
And yes I use 2 different computer as well, one has a gtx1070 the other pc a rx5700xt.
Same issue on both pc.
The Samsung has HDR enabled indeed, I have to disable HDR to apply a icc profile
Comment 9 Zamundaaa 2026-01-20 13:51:40 UTC
Besides the dark areas looking a tad darker in Firefox than Chromium and Chrome (unstable) for some reason, it looks okay on both my laptop and HDR screen with all of the browsers, with the banding being present but not too bad. It's certainly not nearly as bad as in your photo, and looks roughly the same in mpv as well, so I'm relatively sure the browsers aren't messing anything up in general.

As the default is to just pass sRGB content to the screen unmodified, I'm certain that there's no problem in KWin either though.

For your SDR displays, it's reasonable that a different color profile fits them better than the default, that's why the setting is there.
For the HDR mode, if your TV does some processing that needs to be un-done, or you simply prefer the visuals with black levels crushed, you can follow bug 514239 for the ability to set an ICC profile.
Comment 10 tails_lol 2026-01-21 11:23:14 UTC
(In reply to Zamundaaa from comment #9)
> Besides the dark areas looking a tad darker in Firefox than Chromium and
> Chrome (unstable) for some reason, it looks okay on both my laptop and HDR
> screen with all of the browsers, with the banding being present but not too
> bad. It's certainly not nearly as bad as in your photo, and looks roughly
> the same in mpv as well, so I'm relatively sure the browsers aren't messing
> anything up in general.
> 
> As the default is to just pass sRGB content to the screen unmodified, I'm
> certain that there's no problem in KWin either though.
> 
> For your SDR displays, it's reasonable that a different color profile fits
> them better than the default, that's why the setting is there.
> For the HDR mode, if your TV does some processing that needs to be un-done,
> or you simply prefer the visuals with black levels crushed, you can follow
> bug 514239 for the ability to set an ICC profile.

You speaks like everything is normal or if this is a Me problem...
As I said the problem is only in linux.
Not on windows default profile. And not in Android default profile... The image is not crushed, in OTHER os it look closer to the fixed profile.
Comment 11 Alex Folland 2026-01-21 19:39:32 UTC
I have an OLED panel (ASUS ROG STRIX XG27AQDMG) with HDR enabled in the monitor settings, Plasma display settings, and firefox (with about:config preference "gfx.wayland.hdr" set to "true" and "gfx.wayland.hdr.force-enabled" set to "true"; are these enabled for you?  firefox doesn't render in HDR without them).

The sample video https://www.youtube.com/watch?v=s4FnAOg6N5c at 0:43 and 0:44 on the right side where that black patch is doesn't exhibit excessive broken banding like in attachment 188688 [details] for me in Firefox.  It looks more like attachment 188689 [details], but better than that in person.  I realize camera photos don't look accurately represent what you're seeing on your display so I'm writing this with that understanding.

In my plasma display settings, RGB range is set to "Automatic", color accuracy is set to "Prefer efficiency", color resolution is set to "Automatic (10 bits per color)", and brightness for that display is set to 50%.  Here is my kinfo showing KDE Plasma information as well.

❯ kinfo
Operating System: CachyOS Linux 
KDE Plasma Version: 6.5.5
KDE Frameworks Version: 6.22.0
Qt Version: 6.10.1
Kernel Version: 6.18.6-2-cachyos (64-bit)
Graphics Platform: Wayland
Processors: 32 × AMD Ryzen 9 9950X3D 16-Core Processor
Memory: 128 GiB of RAM (123.5 GiB usable)
Graphics Processor 1: AMD Radeon RX 7900 XT
Graphics Processor 2: AMD Ryzen 9 9950X3D 16-Core Processor

So, in conclusion, I don't see the same issue with my system and the settings I described.  I realize that may be unsatisfying, but I'm just adding more data to the issue.  I still believe it's possible the issue you're seeing is a bug in KDE Plasma, but if it is, the settings and hardware I have don't reproduce it.
Comment 12 tails_lol 2026-01-21 21:36:00 UTC
(In reply to Alex Folland from comment #11)
> I have an OLED panel (ASUS ROG STRIX XG27AQDMG) with HDR enabled in the
> monitor settings, Plasma display settings, and firefox (with about:config
> preference "gfx.wayland.hdr" set to "true" and
> "gfx.wayland.hdr.force-enabled" set to "true"; are these enabled for you? 
> firefox doesn't render in HDR without them).
> 
> The sample video https://www.youtube.com/watch?v=s4FnAOg6N5c at 0:43 and
> 0:44 on the right side where that black patch is doesn't exhibit excessive
> broken banding like in attachment 188688 [details] for me in Firefox.  It
> looks more like attachment 188689 [details], but better than that in person.
> I realize camera photos don't look accurately represent what you're seeing
> on your display so I'm writing this with that understanding.
> 
> In my plasma display settings, RGB range is set to "Automatic", color
> accuracy is set to "Prefer efficiency", color resolution is set to
> "Automatic (10 bits per color)", and brightness for that display is set to
> 50%.  Here is my kinfo showing KDE Plasma information as well.
> 
> ❯ kinfo
> Operating System: CachyOS Linux 
> KDE Plasma Version: 6.5.5
> KDE Frameworks Version: 6.22.0
> Qt Version: 6.10.1
> Kernel Version: 6.18.6-2-cachyos (64-bit)
> Graphics Platform: Wayland
> Processors: 32 × AMD Ryzen 9 9950X3D 16-Core Processor
> Memory: 128 GiB of RAM (123.5 GiB usable)
> Graphics Processor 1: AMD Radeon RX 7900 XT
> Graphics Processor 2: AMD Ryzen 9 9950X3D 16-Core Processor
> 
> So, in conclusion, I don't see the same issue with my system and the
> settings I described.  I realize that may be unsatisfying, but I'm just
> adding more data to the issue.  I still believe it's possible the issue
> you're seeing is a bug in KDE Plasma, but if it is, the settings and
> hardware I have don't reproduce it.
using mostly chrome for hdr content.
but thx for the flags.