HD TV monitor, picture is better with VGA than HDMI?

[paddyb]

I’m trying to set up an LG Flatron M2280D Monitor TV with my PC and am having problems getting a decent picture via HDMI.

I have previously been using to quite old 4:3 panels, one connected by VGA, the other by DVI. I want to replace one of them with the LG, but when I connected it via HDMI, the picture produced didn’t seem very sharp, the older monitor was much better. I then tried connecting the LG via VGA and the picture was much better, though I still think it could be improved upon.

This seems confusing to me, surely the digital connection should be sharper? I now also tried connecting via DVI and used different cables and I’m still getting the same results, though now the picture size has also shrunk by about an inch around the edge! I’ve looked at display settings (on PC and TV), have disconnected the second display, checked display adaptor drivers (ATI Radeon 4300) but nothing makes any difference.

Am I missing something here?

 

[CaptainCrash]

On many TVs you have to specifically name the HDMI input label you're using with a PC as "PC" (unsurprisingly), otherwise it won't switch off any image enhancing features which are good for TV/video use but bad when you're trying to use it as a monitor.*

I guess you've already checked that you're running the panel at its native resolution, but you should also check that you're using 1:1 pixel mapping for the PC HDMI input (IIRC LG call it "Just Scan"), and that no other settings either in the TV setup menu or the video card drivers are causing over/underscan.

Finally, some TVs won't accept a full 4:4:4 chroma signal from a PC through their HDMI inputs but instead subsample to 4:2:0, which can cause blurriness particularly with text (they'll always do 4:4:4 chroma over VGA). I'd have thought this was unlikely if it was sold specifically as a combined TV/PC monitor, but it's possible I guess.

*edit: I've just checked your TV's user manual here: http://www.lg.com/us/support-product/lg-M2280D-PU# and it does in fact specifically say: "If you want to use HDMI-PC mode, you must set the input label to the PC mode," so you might want to look at that first if you haven't done it already.

 

[paddyb]

Thanks for your reply.

I'd already found the PC input setting. It did improve things, but not much. Text is still blurry. There is a "Just Scan" option under Aspect Ratio, but it is greyed out. I can't find any other options on the TV and I've gone through most of the Windows display settings. Are there any other Windows settings I should look at?

 

[CaptainCrash]

There is a "Just Scan" option under Aspect Ratio, but it is greyed out.

Just to be absolutely clear, have you definitely set your video card to output at the panel's 1920x1080 native resolution? (Just Scan probably won't work if the display resolution and the incoming signal are not the same).

 

[paddyb]

Just to be absolutely clear, have you definitely set your video card to output at the panel's 1920x1080 native resolution? (Just Scan probably won't work if the display resolution and the incoming signal are not the same).

In Advanced Display Settings in Windows I've set it to 1920x1080, is this what you mean? I can't find any way to directly configure the graphics card.

 

[CaptainCrash]

In Advanced Display Settings in Windows I've set it to 1920x1080, is this what you mean? I can't find any way to directly configure the graphics card.

Yes, that should do it, but...

... I haven't personally used an ATI/AMD card in ages, but after I posted I vaguely remembered "something I read on the web" about undefeatable underscan weirdness in some circumstances. A quick google brought up a fair few hits - you could try this registry fix and see what happens: https://community.amd.com/thread/184967 . After you've applied the fix and rebooted, check the TV menu again and see if Just Scan is now available.

The same problem is also discussed here: https://superuser.com/questions/458...scan-settings-without-catalyst-control-center .

Other than that I'm out of ideas, but from what you're describing it does sound like an overscan/underscan issue.

edit:more reading material here

 

[paddyb]

Ok, the registry fix seemed to do the trick! Thanks very much for your help with this, I would never have worked out what to even google without your help. I can't believe how difficult this was!

 

[CaptainCrash]

You're welcome, glad you got it sorted.