Thank you! It would be great to read something on this topic.
who can use Linux but not windows? Share your Linux setup
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It seems they use displays that can show 10 or 12 bits. This is the maximum for some cards and doesn't allow them to dither. They broke something in the Linux kernel for the 10/12-bit modes for some AMD cards, which seems to have caused dithering. Then they fixed it. This fix has been in the kernel for about two years.
I have come across comments in the amdgpu kernel module code stating that for some cards, dithering should not be enabled at 12 bits. For older cards, I think this value could be 10 bits.
WhisperingWind oh interesting so turning it off on driver side at least will prevent os dithering. Lubuntu does sound promising. I did try HiveOS when I use to mine crypto and the desktop booting felt comfortable when I tried it on a amd igpu. I think lubuntu is similar with using open box/x11. I think lubuntu has the compositor disabled default right ? Assuming that would be better ? WhisperingWind Ahh okay. Tbh it might be more trouble than it's worth. I probably would just find a 2018 Mac mini in that case but I think for now I'll try the hardware I currently got.
I emailed the vpixx/psychtool box company and they told me they personally use the Rx 6600 with ubuntu but they said it requires this tool: https://gitlab.freedesktop.org/tomstdenis/umr to disable dithering.
They also gave me a method on example code for checking dithering with a frame grabber but videodiff I think already exists for that on GitHub.
WhisperingWind Visible changes only occurred after modifying the i915 code
It'd be awesome if you could share what you changed (and how you compiled it).
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I made a spontaneous large number of edits in the i915 module and it seems I forced a smaller number of bits per channel, which resulted in improvements on my monitor with FRC. Later, after studying the i915 code more carefully, I realized that dithering for Intel iGPU is disabled by default in the i915 (except for 6 bits in certain modes). I additionally removed these 6-bit checks from the i915 code so that dithering would not be enabled. I will check if there is dithering at 6 bits on the vanilla kernel, then I can post the fix along with the build guide. But it is only for intel igpu and 6 bit mode.
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Recently installed Zorin OS 15 lite:
Display: ASUS VA249HE (24 inch)
Panel: VA 8-bit or 6-bit, conflicting data on the web
Resolution: 1920x1080
Brightness: 100% - i sit in a sunlit room
Refresh rate: 77hz
Graphics Card: Intel N95 that includes: Intel Corporation Device 46d2
Cable: HDMI
OS: Zorin OS 15 Lite (based on ubuntu 18.04 + XFCE). Disabled compositing. Disabled font aliasing in the OS. Using Firefox - disabled hardware acceleration.
Eyestrain: Eyestrain free
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Please answer a few questions when you have time.
- If you enable hardware acceleration in OS / Firefox, will your eyes feel strained?
- How intense will it be?
- Will the issue recur when watching videos and reading text?
- Could you try focusing your gaze on the dot of the letter "i." Will it feel like your gaze wants to slip off with hardware acceleration on and off?
Sorry for the many questions; I'm just trying to understand how hardware acceleration affects comfort in Linux.
When i use hardware acceleration, for reading text ,for a few minutes i feel much more tension in my stomach , and a slight pain in my right temple. Not so without.
I think it's harder to focus on the dot of the i in the hardware accelerated case, but either case it's not easy. i wear glasses and it's been a long time since replacing them, so maybe i need to get new ones.
as for movies, i'll try next.
WhisperingWind I tested when watching an action 60fps youtube video.
video on full screen. Overlaid on a small part of the screen, the task manager.
Similar percentage of processor use, either with hardware acceleration, or without.
Same goes for chromium.
Something is weird.
Thanks for the reply!
Is there a feeling that on a white background around the letters, there is some kind of movement, like some small dynamic "noise" in the image?
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For me on "bad screens", what I see around letters is a blue glow.
The first time I was able to notice this was after I used a good screen for a few hours with a pure red screen filter, i.e. blue and green was entirely disabled (NegativeScreen app).
After doing that, I looked at a bad screen again, and both these bluish glows around text and other contrasting items + weird extra "subtle shadows" around UI elements was suuuuuuper obvious to me
Another really interesting difference between bad screens and my "one good screen" is on that good screen, using a pure red screen filter looks entirely red, I do not see any other colors at all even while scrolling.
On essentially all other screens, even though I can confirm that only red subpixels are activated with a macro camera, I still see "green and blue trails" while motion happens on the screen (and sometimes, even when there's no motion, I can see green+blue+yellow colors vibrating at edges of contrasting objects that increases when I move my head around). Macs are especially bad with this. In addition, setting most screens to only use blue pixels will show red motion trails.
I don't think it's the other pixels "secretly" activating, they look like they are disabled, but more about how the way the LCD RGB color filters were physically manufactured somehow creates more than just the color they're supposed to. It also might be connected to LCD response time "overdrive" methods as those are frequently associated with colored motion trails.
The strangest part about this though is how my "one good screen" mysteriously is a total outlier here, since it doesn't have the above issue at all.
I got curious and installed Lubuntu as well. By default, I'm experiencing screen tearing in the OS. It seems like there's no hardware acceleration in browsers because 4K videos are choppy. However, when I enter about:support in the Firefox search bar, I see "Compositing: WebRender," which indicates the presence of hardware acceleration
You can check hardware acceleration state at about:support page, look at Compositing row. If there's WebRender, you're running on hardware. If there's WebRender (software) you're on non-accelerated backend.
(https://fedoraproject.org/wiki/Firefox_Hardware_acceleration).
But it seems like something is not quite right.
WhisperingWind from the link you sent, i think webRenderer=true is related to web page rendering, but there are other flags for media acceleration.
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I need to first verify if Intel iGPU has 6-bit dithering enabled by default in the vanilla kernel. If that's the case, then the fix makes sense, and I'll be sure to add the information to the wiki.
When i use hardware acceleration, for reading text ,for a few minutes i feel much more tension in my stomach , and a slight pain in my right temple. Not so without.
Is there an option to connect via DP and switch to 6-bit? I have checked online, and it seems your monitor is true 8-bit, but out of curiosity, you could try switching to 6-bit, as sometimes manufacturers change display suppliers and the displays themselves without notifying the buyer. I switched to 6-bit on my monitor in Lubuntu, and the image is quite pleasing to the eye, and the text is fairly easy to read.
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