LG OLED as PC Monitor: The bad and the good

[orangpelupa]

Are you planning to use an LG OLED TV as a monitor? Sitting at normal monitor distance? LG C1 still uses the same panel as CX, but G1 uses a different panel. So I don't know this is also relevant for G1 or not.

Anyway,

The bad

chromatic aberration or color bleed



This is what has been bugging me the most. LG OLED technology has issues with showing yellow or bright green.

For office work, it's a non-issue, as it only made some icon on MS word looks weird. For design work, it's quite annoying. For example, I'm designing a fabulous yellow box. BAM! On its left side, it will bleed red, and on its right side, it bleeds green. For gaming, it only became an issue in games with solid colors like Hyper Light Drifter and Fez. Or on UX elements in Destiny 2 and Cyberpunk 2077. by the way, for web browsing, chromium-based web browsers like Chrome and Edge have more severe color bleed on text than Firefox.

color shift



This is practically invisible while gaming and writing on ms word. But when you are doing design work, it's a wee bit annoying. Straight in front of you, LG OLED will have proper color for around 10-inch size. But wider than that, the color became cooler. You need to shift your head laterally to the left or right to see them in the correct color.

color banding




For some unknown reason, for years, LG OLED got issues with color banding when used with a PC. Googling around I found these:



How to fix it? Simply use limited range at 8 bit instead of full at 8 bit or 12 bit.

brightness change
Non-issue for gaming and writing on ms word. A wee bit of an issue when doing design work as your eyes will take a few seconds to get accustomed to the new brightness to correctly perceive the colors you've painstakingly designed.

screen shift
I don't think this is an issue, as no one really cares that one of the edges is chopped off a few millimeters. It just looks weird seeing your speaker icon got chopped off a bit. Or windows' running app marker suddenly became very thin or even completely gone.

The good!
It's an awesome screen. I'll share my story with data from rtings for this

HDR
Playing Cyberpunk 2077 with HDR enabled in a completely dark room is simply marvelous. When I'm driving under a building shadow, then into the sunshine. Or when I'm walking from one stall to another in the night. It not only looks amazing but also felt amazing. It really emulates the real sensation of walking in a real-life stall in the night, from one blinding neon to another.

Low Audio and Video latency
basically, this means that moving the mouse cursor felt instantaneous, and playing games not only feels good but also sounds good. So you will hear a gunshot right when you pressed the fire button and see the gun firing.

This is also good for those that do audio design, I suppose.

Real black
Even boring stuff like the dark theme on Windows 10, and dark websites (i use dark reader extension), felt easier to my eyes. SDR games also look amazing, especially games with high contrasting colors like tons of indie games and any games where you fly a spaceship in space.

 

[Zaphod]

chromatic aberration or color bleed

Some kind of subpixel offset issue, due to the layout not being RGB. (GRWB?)

Looks like it could be pretty annoying for text and contrast edges at typical monitor viewing distances. You'd think they would correct for that somehow, at least in a dedicated monitor mode or with some setting, somewhere, but perhaps not? It's probably not an issue for the majority of customers use cases.

 

[digitalwanderer]

I give his report an "A"!

 

[orangpelupa]

Some kind of subpixel offset issue, due to the layout not being RGB. (GRWB?)

Looks like it could be pretty annoying for text and contrast edges at typical monitor viewing distances. You'd think they would correct for that somehow, at least in a dedicated monitor mode or with some setting, somewhere, but perhaps not? It's probably not an issue for the majority of customers use cases.

Yeah, seems to be an inherent "flaw" due to the subpixels design.

The weird thing is that this also happens on the 48" lg oled that was marketed as a gaming monitor alternative.

Although to be fair, the color bleed only occur on few games haha.

So yeah, most users probably won't ever have this problem

 

[WhiningKhan]

I was just barely able to notice the red subpixel in the left edge and green on right last evening, looking at Netflix Test patterns yellow text at about 15cm distance on my 55 CX. But it is there.

I really don't understand the logic causing it though.

 

[orangpelupa]

I was just barely able to notice the red subpixel in the left edge and green on right last evening, looking at Netflix Test patterns yellow text at about 15cm distance on my 55 CX. But it is there.

I really don't understand the logic causing it though.

Zaphod's explanation seems spot-on. As again and again, non-RGB subpixels screens always have weird artifacts like this. LG OLED use RWBG subpixels. Samsung SAMOLED use RGGB IIRC (and it results in white text looks like having red color bleed or chromatic aberration).

THe weird thing, is that my old LCD LG TV was WRGB and it have none of this color bleed issue. It does have yellows issue tho (yellows look really-really weird, no matter what setting).

 

[Silent_Buddha]

screen shift
I don't think this is an issue, as no one really cares that one of the edges is chopped off a few millimeters. It just looks weird seeing your speaker icon got chopped off a bit. Or windows' running app marker suddenly became very thin or even completely gone.

This isn't a limitation of OLED TV's but a limitation of large screen TVs combined with how LCD and OLED panels are made. The same thing happens on my LCD TV that I use for a monitor. Especially noticable when part of an entire row of icons at the edge of the display just disappears as you move your head towards the other edge and then comes back when you move your head back towards those icons.

It's why I'm sad that curved TVs have pretty much disappeared.

Regards,
SB

 

[orangpelupa]

This isn't a limitation of OLED TV's but a limitation of large screen TVs combined with how LCD and OLED panels are made. The same thing happens on my LCD TV that I use for a monitor. Especially noticable when part of an entire row of icons at the edge of the display just disappears as you move your head towards the other edge and then comes back when you move your head back towards those icons.

It's why I'm sad that curved TVs have pretty much disappeared.

Regards,
SB

I think that's a different issue that only occurs on IPS LCD, not occurs on TN LCD, not occurs on VA LCD, and not on OLED.
at least that was my experience with LG IPS LCD, ViewSonic and Changhong TN LCD, TCL VA LCD, and LG OLED.

Dunno how its behavior on Samsung PLS LCD or Samsung mini LED, as I had never got my hands (eyes?) on them haha.

on OLED, the screen shift digitally moves the whole screen to reduce burn-in risk. So sometimes a few mm from the left offset (thus chopping off a few mm on the right side), sometimes it's the opposite. Offset a few mm from the right (thus chopping off a few mm on the left side).

it doesn't matter when you move your head to that edge. The pixels will still get chopped off. because the TV system did chop them off.

 

[WhiningKhan]

Zaphod's explanation seems spot-on. As again and again, non-RGB subpixels screens always have weird artifacts like this. LG OLED use RWBG subpixels.

I know that but why the hell does it turn on the green subpixel on a pixel which is supposed to be fully white while adjacent pixel is perfectly yellow as it should be?

 

[orangpelupa]

I know that but why the hell does it turn on the green subpixel on a pixel which is supposed to be fully white while adjacent pixel is perfectly yellow as it should be?

Yeah, it's showing a blank gap (green turned off) would be better than this color bleed, I think

Or maybe because yellow is a mix of red and green? And the gap between red subpixels and green subpixels are simply too far apart, making the green color bleed on the right and yellow on the left

for example, showing yellow, 3 pixels wide, using this subpixels, with "dot" simbolize pixel gap, and underscores symbolize turned off subpixels.



RWBG.RWBG.RWBG

Showing yellow means

R__G.R__G.R__G

Thus the left edge bleeds red because R is too far apart from G.

Thus right edge bleeds green because G is too far apart from R

 

[London Geezer]

I must say, I never heard or seen that colour banding but needless to say, that is not working as designed so it's good that you found a 'fix'. Those pictures you posted would be enough for me to return the TV and never look at it again, they gave me a headache just looking at them on my laptop.

 

[orangpelupa]

I must say, I never heard or seen that colour banding but needless to say, that is not working as designed so it's good that you found a 'fix'. Those pictures you posted would be enough for me to return the TV and never look at it again, they gave me a headache just looking at them on my laptop.

The only "fix" is by sitting further away hahaha.

Anyway, most people are unable to see this. Even rtings missed it in their reviews until readers starts telling them. Heck, HDTVtest (well known tv reviewer and professional calibrator) hasn't even noticed it yet, I think

 

[orangpelupa]

Yeah, it's showing a blank gap (green turned off) would be better than this color bleed, I think

Or maybe because yellow is a mix of red and green? And the gap between red subpixels and green subpixels are simply too far apart, making the green color bleed on the right and yellow on the left

for example, showing yellow, 3 pixels wide, using this subpixels, with "dot" simbolize pixel gap, and underscores symbolize turned off subpixels.



RWBG.RWBG.RWBG

Showing yellow means

R__G.R__G.R__G

Thus the left edge bleeds red because R is too far apart from G.

Thus right edge bleeds green because G is too far apart from R

This got me thinking, if LG add an option to "fuzz yellow to eliminate color bleed" they can do this (to display 3 pixels-wide yellow) for example:

instead of
R__G.R__G.R__G
and results in color bleed

inaccurately display it as
G.R__G.R__G.R__G.R

voila, no more color bleed (probably, lol)

 

[London Geezer]

The only "fix" is by sitting further away hahaha.

Anyway, most people are unable to see this. Even rtings missed it in their reviews until readers starts telling them. Heck, HDTVtest (well known tv reviewer and professional calibrator) hasn't even noticed it yet, I think

Mmmm I am very suspicious of this then. I’d never heard of this and the best (or any) reviewers/calibrators never noticed?

 

[WhiningKhan]

Yeah, it's showing a blank gap (green turned off) would be better than this color bleed, I think

Or maybe because yellow is a mix of red and green? And the gap between red subpixels and green subpixels are simply too far apart, making the green color bleed on the right and yellow on the left

for example, showing yellow, 3 pixels wide, using this subpixels, with "dot" simbolize pixel gap, and underscores symbolize turned off subpixels.



RWBG.RWBG.RWBG

Showing yellow means

R__G.R__G.R__G

Thus the left edge bleeds red because R is too far apart from G.

Thus right edge bleeds green because G is too far apart from R

Yes, I'm still with you and I understand why it looks like it does but I still don't understand why they do it like that. It looks like as if there is a one pixel offset between luma and chroma... Couldn't they just 'start every pixel' with W and form the color with BGR. If the panel in reality is arranged as RWBG, this needs an address offset between the components which I imagine is completely trivial compared to other stuff the image processor is doing. The leftmost and rightmost pixel rows of panel would be the only ones possibly distorted then, right?

 

[swaaye]

Are you sure you're not feeding it YUV 422/420 instead of RGB? That definitely gives text chroma bleed.

My cheapo Vizio Quantum TV-as-monitor has some terrible behavior where it actually converts incoming RGB to YUV 422 or something. I used to just run YUV 444 which was alright but I figured out if I make a custom resolution using CVT timings that it will run straight RGB as well.

I have a LG C7 65 in the living room where it is also used with a PC for games. I should look closer at it. Obviously most of the time I'm far away from it.

 

[orangpelupa]

Mmmm I am very suspicious of this then. I’d never heard of this and the best (or any) reviewers/calibrators never noticed?

Seems only a very small population of human able to see it easily. But

Heck, rtings only added info about this issue on their 48" LG CX because they were told by readers. They still hadn't put it into their official tests on any other TV (including 55 inch LG CX)

here's from rtings

"Update 09/22/2020: We received reports of people noticing vertical red lines appearing when displaying yellow or green. We recreated this issue and updated the text; see below for details."
https://www.rtings.com/monitor/reviews/lg/48-cx-oled

Are you sure you're not feeding it YUV 422/420 instead of RGB? That definitely gives text chroma bleed.

My cheapo Vizio Quantum TV-as-monitor has some terrible behavior where it actually converts incoming RGB to YUV 422 or something. I used to just run YUV 444 which was alright but I figured out if I make a custom resolution using CVT timings that it will run straight RGB as well.

I have a LG C7 65 in the living room where it is also used with a PC for games. I should look closer at it. Obviously most of the time I'm far away from it.

yeah, I'm on RGB.

Rtings actually recommends using YUV 420 (or YUV 422, can't remember) to reduce the color bleed. But to my eyes, YUV 420 and 422 only make texts look even worse and didn't fix the yellow color bleed (but it does change how the bleed looks into less noticeable). YUV 444 have no effect to the yellow color bleed at all (to my eyes identical bleeding with RGB)

 

[Xmas]

Or maybe because yellow is a mix of red and green? And the gap between red subpixels and green subpixels are simply too far apart, making the green color bleed on the right and yellow on the left

for example, showing yellow, 3 pixels wide, using this subpixels, with "dot" simbolize pixel gap, and underscores symbolize turned off subpixels.



RWBG.RWBG.RWBG

Showing yellow means

R__G.R__G.R__G

Thus the left edge bleeds red because R is too far apart from G.

Thus right edge bleeds green because G is too far apart from R

Yes, looking at the pictures closely it seems to me this is exactly what happens. I'm surprised they don't use blue as an edge subpixel, given its lower luminance contribution and lower perceptual resolution. And there doesn't seem to be much of a pixel gap to speak of. I wonder if RWGB would be a better subpixel order regarding colour bleed (you'd still get some red/blue bleed for purple), and what an RGB stripe with a white horizontal bar above would look like.

 

[WhiningKhan]

I'm surprised they don't use blue as an edge subpixel, given its lower luminance contribution and lower perceptual resolution.

Exactly. I don't know how tightly hardwired the pixel/subpixel relationship is internally, but shifting the red component to the next physical pixel would give WBGR which might be much better. Maybe.

 

[Zaphod]

Exactly. I don't know how tightly hardwired the pixel/subpixel relationship is internally, but shifting the red component to the next physical pixel would give WBGR which might be much better. Maybe.

https://fwd.nl/app/uploads/LG-OLED65G1RLA-pixels-1080x600.jpg
https://www.avsforum.com/attachments/screen-shot-2020-03-07-at-4-11-27-pm-png.2694776/

When I read some stuff from an older LG oled tech presentation (probably 2018-2019) it was all about sustained luminosity (shortening wiring distance to decrease dead space), though it is not clear to me why the chosen layout best achieves this. Text rendering and other high contrast edges on static images was probably way down the priority list of use cases to care much about.