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Zenurik · (Last edited: 01-11-2021, 04:02 PM by Zenurik)

Hello, I'm new around here so excuse my lack of knowledge. I switched my output from VGA to HDMI for the first time recently (because new Nvidia GPU) and I've been having an issue with colors (especially reds and blues) looking like they are bleeding/blurry or on a badly youtube compressed video. I've searched for it and found about the limited color range, but switching to "Complete" both on the NVidia control panel and my monitor's settings doesn't help.

I found these forums through this article saying it's because my monitor is being recognized as a TV and thus isn't sending the correct color signal, which appears to be the case, as is shown in the attached image, hopefully.

Switching to any "PC" listed resolution makes the issue disappear but there is no native 1080p there.

I've tried using the CRU tool but I'm not sure what I should do and I'm afraid of breaking something. Any help is appreaciated

***ToastyX*** · 01-11-2021, 05:15 PM

Your screen shot cut off the color settings. You need to change the color format. The monitor probably expects RGB. YCbCr 4:2:2 can cause the problem you're seeing. YCbCr 4:4:4 should be fine, but the monitor might convert YCbCr 4:4:4 to 4:2:2 internally.

Zenurik · 01-11-2021, 05:54 PM

(01-11-2021 05:15 PM)ToastyX Wrote: Your screen shot cut off the color settings. You need to change the color format. The monitor probably expects RGB. YCbCr 4:2:2 can cause the problem you're seeing. YCbCr 4:4:4 should be fine, but the monitor might convert YCbCr 4:4:4 to 4:2:2 internally.

Oops, sorry. Here it is in full

I tried all three modes RGB/YCbCr422/444 but they don't seem to make any difference.

***ToastyX*** · 01-11-2021, 06:23 PM

Then the monitor is not handling HDMI signals correctly. What monitor is it?

If you use CRU and delete the "HDMI support" data block in the CTA-861 extension block, that will make the GPU send a DVI signal instead, which the monitor might display correctly.

Zenurik · (Last edited: 01-11-2021, 07:55 PM by Zenurik)

(01-11-2021 06:23 PM)ToastyX Wrote: Then the monitor is not handling HDMI signals correctly. What monitor is it?

If you use CRU and delete the "HDMI support" data block in the CTA-861 extension block, that will make the GPU send a DVI signal instead, which the monitor might display correctly.

It's a Samsung T27A550, quite old but still a good TV-monitor IMO. And interestingly, there are two HDMI ports and the one I'm connecting to is labled as "HDMI (DVI)" the other doesn't say anything and doesn't output my video for some reason.

I did what you described and restarted the GPU drivers but the issue persists. Did I miss anything?

[EDIT]: Nevermind, I tested the second input again and it worked; the color bleeding persists but now Nvidia's control panel displays the connection as "DVI - PC Video" - But I suppose that's because I removed the HDMI support.

***ToastyX*** · 01-11-2021, 08:44 PM

That's definitely the monitor messing with the resolution then. It might only be doing that for TV resolutions. If there's a TV resolutions data block in the extension block, delete it. Then edit the 1920x1080 @ 60 Hz detailed resolution to use "CVT-RB standard" timing. The monitor might treat that differently and display it normally.

Zenurik · (Last edited: 01-11-2021, 09:49 PM by Zenurik)

(01-11-2021 08:44 PM)ToastyX Wrote: That's definitely the monitor messing with the resolution then. It might only be doing that for TV resolutions. If there's a TV resolutions data block in the extension block, delete it. Then edit the 1920x1080 @ 60 Hz detailed resolution to use "CVT-RB standard" timing. The monitor might treat that differently and display it normally.

Still the same unfortunately; although now Nvidia's control panel reports the display resolution as "PC - 1080p native". I also tested the CVT-BR timing along with all the others (restarting the driver each time) and even removing the "HDMI support" data block again, but they don't seem to help either.

I guess we are trying to trick the monitor into seeing the resolution as a "PC video" instead of "HDTV", right? Could the cable I'm using be interfering with anything?

***ToastyX*** · 01-11-2021, 10:10 PM

(01-11-2021 09:48 PM)Zenurik Wrote: I guess we are trying to trick the monitor into seeing the resolution as a "PC video" instead of "HDTV", right? Could the cable I'm using be interfering with anything?

Really there's no difference. The monitor is messing with the image, probably converting to YCbCr 4:2:2 internally. I was hoping it was only doing that to CTA-861 standard timing parameters commonly used with TVs, but it seems to be doing that for all timing parameters.

You might have to get an HDMI-VGA active adapter to work around the problem.

Zenurik · (Last edited: 01-11-2021, 11:26 PM by Zenurik)

(01-11-2021 10:10 PM)ToastyX Wrote:
(01-11-2021 09:48 PM)Zenurik Wrote: I guess we are trying to trick the monitor into seeing the resolution as a "PC video" instead of "HDTV", right? Could the cable I'm using be interfering with anything?
Really there's no difference. The monitor is messing with the image, probably converting to YCbCr 4:2:2 internally. I was hoping it was only doing that to CTA-861 standard timing parameters commonly used with TVs, but it seems to be doing that for all timing parameters.
You might have to get an HDMI-VGA active adapter to work around the problem.

I see, that's quite annoying.. But I was thinking the same, connecting the HDMI cable through a VGA adapter directly into the "PC"-labled input is probably the solution. Since the monitor is primarily sold as a TV, the HDMI ports probably weren't made for computer use.

I was wondering though, could that cause any loss in throughput, signal etc.? Would it still be recognized as a digital signal? VGA was kind of a pain sometimes due to me having to calibrate the clock and phase all the time to have a sharp image. Also, what do you mean by VGA *active* adapter? Is there any other type I should be aware of?

***ToastyX*** · 01-12-2021, 01:10 AM

Active means it converts the signal from HDMI to VGA. HDMI-VGA adapters are always active, so you don't have to worry about that. Passive adapters simply change the plug without converting the signal, but that's not possible with HDMI to VGA. The video card will see it as an HDMI or DVI monitor. HDMI-VGA adapters support 1080p, so that shouldn't be a problem. You would still have to calibrate the clock and phase, but auto adjust should work well if you display a checkerboard pixel pattern like this: https://www.monitortests.com/png/pattern-1920x1080.png