Hello - I am wondering what Linux distros, versions, driver version, windows manager, etc your using that works with no issues. Also would like to know what gpu. i was thinking of giving arch Linux a try but curious what other distros also are fine and what settings and such make it better? In terms of disabling dithering, font smoothing and such.

I use latest Lubuntu , 22.04 , on Intel nuc95 as is(even live USB worked well) , chrome with no HW acceleration. The display is: VA249HE . Lubuntu also worked without strain on another desktop, stronger one, Intel integrated graphics, now HW not working, so I can't tell more about it.

A couple of months ago, I was experimenting with the Blackmagic UltraStudio Recorder 3G, recording uncompressed 10-bit video from my MBP M1. At that time, I was already using Stillcolor (the application that disables dithering in macOS). I also had Ubuntu 22.04, which I installed on a Parallels virtual machine in macOS. I decided to try recording and analyzing the desktop in Ubuntu. There was no dithering, neither in macOS nor in Ubuntu 22.04. When I enabled dithering in Stillcolor, dithering also appeared in Ubuntu. I don't remember exactly, but it seems Ubuntu was using Wayland, not X11. My hypothesis is this: dithering is influenced only by a driver and a video adapter. In Parallels, the virtual video adapter driver is used, which does not dither, leading to no dithering in Ubuntu when it is run in the virtual machine. However, there's a question about the presence of hardware acceleration in this setup, which I can't yet comment on. But OpenGL is responsible for hardware acceleration. According to the documentation, OpenGL has the GL_DITHER option. **“GL_DITHER - If enabled, dither color components or indexes before they are written to the color buffer.”** I think it is possible to recompile the Linux OpenGL library with GL_DITHER forcibly set to false. At first glance, modifications need to be made only in two places in the library code: 1. prohibit enabling dithering from outside: https://gitlab.freedesktop.org/mesa/mesa/-/blob/main/src/mesa/main/enable.c#L519; 2. find where ctx->Color.DitherFlag is initialized to set it to GL_FALSE. In the kernel, dithering is enabled during the initialization stage of the video adapter (I'm only talking about UHD Intel here). As I understand it, this happens in this i915 module file: https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/i915/display/intel_display.c. I quickly went through the code, and it seems there is a possibility to force 8-bit and disable dithering. The question of hardware acceleration directly in the browser remains. As far as I know, some browsers use WebGL. The question here is whether this library calls the system's OpenGL library or not. I found information that Intel Arc also uses the i915 kernel module, and I'm interested in whether it's possible to disable dithering not only for UHD but also for ARCs. I recently ordered a mini PC based on the i5-12450H processor. I want to set up an additional workspace using it. Since Windows is bad for my eyes, I want to try Linux and see if I can disable dithering for UHD / ARC.

I installed the latest version of Manjaro XFCE on a mini PC (i5-12450H, UHD Graphics (48EU)). Right out of the box, it was very uncomfortable; after a couple of hours, my eyes started to hurt, and it became difficult to work. After making edits in the i915 module, it got better. Noticeable transitions in gradients appeared: https://ibb.co/q1f6Pw4 As for OpenGL, it's still unclear because Manjaro XFCE has several different OpenGL builds, and some of them are loaded, including in the Firefox process. It's not yet clear where to get the code for them (so far, I've identified and rebuild only one of several libraries). But if I make it so that the OpenGL libraries are not used by the OS (hardware acceleration is switched off), it seems to make it easier on the eyes, but this is still unproven and based on feelings. I am currently on a business trip and have limited access to equipment. In a couple of weeks, I will be home and will try to understand the difference between the adjustments to eliminate subjectivity. I will also continue to explore the possibility of rebuilding OpenGL.

I really don't think you need to do that.. static dithering has never been an issue. It's temporal FRC that people have an issue with. It's drivers that might use FRC or hardware in the panel. This gl_dither thing has primarily been used when working with a colour depth that doesn't match e.g. 4 bit and 8 bit. And really, there's an easy way to test.. just don't use opengl as the compositor and you have your answer. XRender is a software-only path for x.org.

@"Sunspark"#p37997 You are right about OpenGL, I can confirm that rebuilding OpenGL libs with dithering disabled did not yield results. Visible changes only occurred after modifying the i915 code. Currently, MBP M1 + Stillcolor seems slightly more comfortable for my eyes than Manjaro with i915 module tweaks (although I'm not 100% sure yet). > And really, there's an easy way to test.. just don't use opengl Without using OpenGL, the text looks different and is easier for me to read. However, I suspect this is not because of specific OpenGL libraries, but rather due to the system rendering fonts differently without any hardware acceleration. I think I'll dig into font rendering and see what can be done here.

> @"Sunspark"#p37997 static dithering has never been an issue. It's temporal FRC that people have an issue with this is mostly true with older devices — but some more modern versions of "spatial dithering" are "semi" dynamic where even though they're still if nothing is happening, the dithering will slightly move around if you're moving your mouse cursor across things (or any similar kind of change to the screen) for example, the dithering in e-ink devices is not really temporal as it's "usually" still, but areas of the screen will "regenerate" an entirely different dithering pattern when any motion happens, which can still cause issues

> @"WhisperingWind"#p37970 experimenting with the Blackmagic UltraStudio Recorder 3G, recording uncompressed 10-bit video from my MBP M1 can you send me some still PNG frames of some macOS apps taken directly from the lossless capture? i want to analyze the colors themselves to see if there are any other (non-temporal) anomalies like color fringing or shadows/halos where there shouldn't be i want to see if there's anything different about the colors that actually get sent to the video output, compared to what e.g. a normal screenshot of the same app looks like

@"WhisperingWind"#p38001 what did you changed in the OpenGL and in i915 code? How did you deployed it? I want to do it too, don’t have a guide?

@"DisplaysShouldNotBeTVs"#p38008 The HDMI recorder is unfortunately at my home. But I am currently on a business trip. At the end of September, I will return home and will be able to record and send the images.

@"twomee"#p38009 I think I can put together a guide and upload the code to GitHub next week.

who can use Linux but not windows? Share your Linux setup

autobot

I'm curious, wouldn't this be a decent strategy(even for games), on the desktop, against strain:

1. Buy a desktop with a strong multi-core CPU, and disable the GPU driver, to use software rendering

2. Use the rendering layers above the GPU that cause the least strain?

moonpie

autobot I'm curious, wouldn't this be a decent strategy(even for games), on the desktop, against strain:

Buy a desktop with a strong multi-core CPU, and disable the GPU driver, to use software rendering

$9,999.00
https://www.newegg.com/amd-threadripper-pro-7995wx-350w-sp6-ryzen-threadripper-7000-series/p/N82E16819113810

My guess is your games will still run at 10fps.

jordan

moonpie jeez pricey. I have two 3995wx thread ripper PCs which are much cheaper but 64core

WhisperingWind

I'm sure that applies to many different monitors too. I wonder what would be the best way to grab the color profile other than grabbing it off a Mac. What PC is this? The a770 one? I was wondering if the a770 is able to be made fully comfortable or to not bother with it

autobot

moonpie What if we disable the GPU, aim at a reasonably expensive fast CPU(for ex. $500-600$), with the goal of running all steam games before a given date(for ex. before 2018) ?

Would this work reasonably well , for those who are willing to settle on the gaming experience?

JTL

WhisperingWind That's an apt yet simplified explanation.

WhisperingWind

DisplaysShouldNotBeTVs

I ran into some color management issues that I need to figure out.

The video recorded by the device uses Limited Range 16-235, which makes white look gray. Switching between Limited Range and Full Range in BetterDisplay for the recorder doesn't fix the issue.

The recorder can also take screenshots (a separate feature from video recording). These screenshots are in TGA format, and in those, the white background in the browser looks white with a value of 255. But there are differences in shades between the screenshots taken directly on the M1 Mac and on the recorder because the profile generated by macOS is not accurate (?). I also tried standard profiles, and it's the same story everywhere; the shades differ.

TGA should be lossless (https://en.wikipedia.org/wiki/Truevision_TGA), but the presence of something similar to aberrations around some colored objects seems strange to me. I need to figure this out as well.

Below are links to screenshots taken directly on my M1 Mac (Screenshot_X.png) and screenshots taken through the HDMI recorder (Recorder_X.tga): https://file.io/7N0aPzOsfdPg

If you need frames directly from the video, let me know, and I'll send those too, but they are in Limited Range 16-235.

DisplaysShouldNotBeTVs

WhisperingWind

the file link isn't loading, it says that it was deleted

can you reupload it again?

DisplaysShouldNotBeTVs

WhisperingWind the presence of something similar to aberrations around some colored objects seems strange to me

if you see this, these are pretty much what's going on

1 (2011, Samsung):

https://www.researchgate.net/publication/241222779_Depth_Perception_Enhancement_based_on_Chromostereopsis

2 (2017):

https://www.rose-hulman.edu/class/cs/csse451/Research%20paper/2019-papers/ChromaBlur.pdf

3 (2018, continuation of 2, funded by Intel Labs):

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6126933/

prior work that eventually lead up to this goes back to the mid-2000s, possibly earlier

https://jov.arvojournals.org/article.aspx?articleid=2121865

WhisperingWind

I came across something interesting. In Linux, if I enable 6-bit color, it seems that the FRC module on a 6bit+FRC monitor continues to strain my eyes a bit when reading. I replaced the Linux profile with the one from macOS. The eye strain when reading text disappeared, and the screen became a bit calmer. I've been testing this for two days now, and there's no mistake - the effect is almost immediate in terms of eye strain when reading text or lack thereof.

It's possible that an incorrect color profile set by default in Linux could have affected color conversion, leading to incorrect interpretation of the 6-bit signal. This might have triggered FRC activation for compensation, even if the output was specifically set to 6-bit. But this is just a hypothesis for now.

WhisperingWind

jordan

The monitor's color profiles have different triangle coordinates (color gamut), different white points, and different gamma. Here's an example comparing two color profiles of my monitor from macOS and Linux. As you can see, there's a shift towards the yellow spectrum in Linux, which theoretically could be interpreted by the monitor as coordinates beyond the 6-bit range (but I'm not an expert in this): https://ibb.co/mRd9YtN

I checked the color profiles for my TV: the triangle coordinates (color gamut) are the same, but the white point and gamma differ, which should not cause dithering at 8+ bits (TV has 8+FRC). This means that not all devices may have the issue; it definitely won't be a problem if the monitor doesn't support FRC.

What PC is this? The a770 one?

I don't know if Windows generates color profiles, but it can be checked.

WhisperingWind

jordan

Try Ubuntu 18, which the autobot installed. It seems that it doesn't support the Xe architecture, on which the A770 is based. It’s necessary to check that the i915 and xe modules are not loaded using the lsmod terminal command.

If Ubuntu 18 is comfortable, so the monitor should be fine and the graphics card in basic mode is also okay. If that's not the case, then there's probably not much that can be done here without changing hardware. But it's hard to say for sure, as everyone has different sensitivity in their eyes, but for me, reading in this case is quite comfortable.

If everything is okay, then you can switch to newer versions of Linux where video card support is available and try different desktop environments with various compositors. Try turning off text anti-aliasing in Ubuntu Tweaks (apt install gnome-tweaks).

P.S. I agree 100% with JTL: you need to understand what specifically strains your eyes (vivid colors, contrast, high brightness of white areas, etc). This way, you'll have a set of small tasks to address, with the ability to check the results. This will be more manageable.

WhisperingWind

The service somehow deleted the uploaded archive. I've re-uploaded it: https://easyupload.io/abm64p

jordan

WhisperingWind okay I will test another time when I'm not flared up. I haven't tried my arc yet.

I do want to mention that I tried the "amd Raphael igpu" from amd ryzen 7950x and it felt comfortable on this setup. This is HiveOS distro - I used it when I was setting up my crypto mining pc. I'm not mining anymore so I think this may be worth to try next for myself. I just wonder what normal distro would be similar to this? I think it uses openbox, x11 and Compton? It felt fine on my VA ccfl tv back around April or so when I tried it. Also is this a different amd driver than normal? It's a mining os so I'm assuming all of the acceleration stuff is disabled for the UI which maybe helps comfort ?

JTL

autobot Won't work.

A better project would be to obtain a "good" setup with an older GPU and study what potentially causes strain with newer setups.

autobot

Installed Zorin os lite 17.2, based

on ubuntu 22.10.

Driver - i915.

Disabled xfce compositor(colors became somewhat muted), disabled font anti-aliasing, disabled firefox "hw acceleration" , disabled firefox "pages choose their own font".

Based on short testing, feels good. But needs more testing.

WhisperingWind

I came across an interesting comment in the kernel (module i915):

'For Display < 13, Bits 5-7 of PIPE MISC represent DITHER BPC with valid values of: 6, 8, 10 BPC.

ADLP+, the bits 5-7 represent PORT OUTPUT BPC with valid values of: 6, 8, 10, 12 BPC.'

I think '13' refers to the 13th generation of Intel; ADLP stands for Alder Lake P.

I wonder if this confirms that ADLP and later generations are free from dithering.

autobot

WhisperingWind That's a great find.

I think we need to look at the programming manual for those registers.

I'll try to find the manual.

autobot

WhisperingWind looking at the manual for "dither" , it says it can be free from dithering, given the right register values.

JTL

autobot You probably want one of these: https://www.intel.com/content/www/us/en/docs/graphics-for-linux/developer-reference/1-0/hardware-specs.html

autobot

JTL thank you, that is very helpful.

I looked there, found this registers manual that includes info about dither registers:

https://cdrdv2-public.intel.com/703047/intel-gfx-prm-osrc-tgl-vol-02-c-command-reference-registers-part-2.pdf

It's iris xe gen 11th but alder lake n is 12th generation, but the registers are Probably the same
And yes, registers 7:5 from PIPE_MISC are responsible for dither_bpc, like the source code

WhisperingWind

My i5-12450H uses PIPE_MISC_A, and the register value in Windows 11 is 00000100000000000000000000000000. Dithering is not enabled by default.

autobot

WhisperingWind

A. There are a few registers interacting, not only from PIPE_MISC, Probably, so we need to understand them and dump them all to test.

B. Another way to test whether its hardware or software or driver creating the issue is to try Zorin Os with gpu and with the settings I mentioned previously.

simplex

WhisperingWind Dithering is not enabled by default.

same for my UHD770 (12600k), also I dont use ditherig for IRIS XE 96EU (13700h)

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