Red Fringe on LCD? Almost Seems Like Convergence Issue! (huh!?!)

H

Hurin

2[H]4U
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Oct 8, 2003
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Okay, I know there's no such thing as old-school convergence on an LCD. I'm actually coming from a CRT. My eyes have gotten too old and though I still love my old Sony for its black levels, contrast, etc. . . I've been lured into 2560x1200 LCD crispness.

I just hooked up my LG W3000H and it looks pretty good. But folder icons and any other icons with stark vertical lines (like document icons) all have a very fine (tiny!) red "fringe" along the left side.

Basically, I just want to know if this is normal for an IPS LCD panel (30"). I don't want to keep something that is defective if I could return it and get one without this (admittedly minor) issue.

Any feedback? Been googling, but haven't found anything really definitive. Would love to get y'all's feedback.

Thanks!
 
Okay, someone check my thinking here and/or please confirm via your own observations of 30" panels. . .

I don't see this red fringing on the LCDs on my laptop, or the 20" TN panel my wife uses.

However, here's what I've been able to ascertain. . .

  • It only shows up on lighter objects against darker backgrounds.
  • LCD pixels are actually made up of three sub-pixels. From left to right, those sub-pixels are red, green, blue.
  • So, I'm seeing the red on the left of these items on black/dark backgrounds because the lighter object has the red sub-pixel lit, which is the leftmost sub-pixel. . . against a black/dark background where no sub-pixels are lit.
  • This is apparent on my new monitor because it is 30" and therefore the sub-pixels are more visible than on more densely populated panels (in other words, the pixels, and therefore the sub-pixels are a bit larger on this display, making the red sub-pixels a bit more apparent).

Sound right?
 
I doubt that's the case. 30" 2560x1600 displays actually have smaller pixels than most PC monitors.
Though your laptop depending on the res, could indeed have smaller pixels.

You can see with this calc here... http://members.ping.de/~sven/dpi.html

Have you tried switching outputs on your video card? Also try switching DVI cables. You are using a DVI-DL cable right?
Could also be the sharpness setting. Check your video cards option and make sure it's not doing any sharpening. Also try the sharpness settings in your monitors OSD.
 
Hi Bummrus[h]a,

Thanks for the input. I don't think it's the cable or the output. I tried it on my wife's computer before hooking it up to mine. Also, it's a digital signal. . . so it's either there or not (off or on), unlike old analog vga signals. The cable is DVI-DL (it came with the monitor and seems to be of high quality). The monitor doesn't actually have a sharpness setting. It's got no OSD at all.

But, finally, I found some documentation of this behavior on the Fujitsu website. It's a PDF (but on a reputable site and I scanned it via malwarebytes and norton). Link.

That completely explains and demontrates the behavior. The only thing it doesn't really answer is why the issue is so much more apparent on this monitor than my others. As you say, the pixel density is better or equivalent to my 20" LCD. So the pixels should be the same size. I can't figure out why I'm seeing it so much more on this new monitor. Something about IPS panels?
 
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Well, I'm 100% sure that what I'm seeing is the red sub-pixel as described in the Fujitsu document above. But what I can't figure out is why it's so much worse than on any other LCD I've now viewed. I have compared this red fringing/shadowing on the left of white text on a black/dark background on the following monitors:

Apple Cinema Display 30"
iMac 24" (newest)
Samsung 204BW
20" Acer TN Panel
two laptops

While all of them exhibit this issue to a very small degree (some more than others). This LG W3000H has a substantially wider red fringe/shadow. Not so big that it looks like it's a different problem. But big enough that you wonder why it's so much worse than those other ones. Is this just the way the LG panel is? Could it possibly vary from panel to panel? Could it just be that the super-saturated reds of this wide gamut panel are making it stand out much more?

If another LG W300H (or Dell owners that use the same panel) could chime in here to let me know if they have the same thing, that would be great. I'm currently about to pull the trigger on an RMA with Newegg.
 
Do you wear glasses? If yes, are they high index (of refraction) or standard?
 
Surly73 said:
Do you wear glasses? If yes, are they high index (of refraction) or standard?
Click to expand...
I don't tend (need) to wear glasses. I have a pair that are largely optional (I basically just wear them at night while driving).

Generally, at the computer, I don't tend to wear them. Though I've tried them while troubleshooting this issue and they don't seem to make a ton of difference.

I have noticed, though, that this may in fact be a subjective thing. The red fringe is much worse when my eyes are tired and/or when there's more ambient light in the room. Though, oddly, the backlight level doesn't seem to make a difference.

I went to bed last night thinking the problem was tolerable because the red fringe was much less distinct. Yet, today (having let the monitor fully warm up again), it's pretty bad again.
 
I was driving at glasses causing it, not correcting it :) Maybe it's time to whip out a digital camera with macro and take a picture of the effect and see what's actually going on. Perhaps this display has a non-typical RGB subpixel layout that is being seriously messed up by ClearType (you have turned Cleartype off, right?)

Longer explanation:

Ever since I went high index years ago the chromatic aberration and uneven refraction of the spectrum would basically make a converged CRT look misconverged unless you looked straight through the sweet spot. Right now on my 2490 if I move my head in a circle I can make blue/red fringes dance.

My unaided eyesight is poor but far from off-the-charts. It's an effect of plastic with a high index even without a severe prescription. I thought maybe this was happening to you.
 
The subpixels on IPS panels are not at the same depth. I think the red subpixels are slightly in front of the other subpixels. That combined with a wider gamut makes the red fringing easier to see.
 
I have seen a couple of users complain about this on their NEC 3090's...
 
I attempted to get an image with my wife's Canon. But despite goofing around with ISO and Macro mode, I couldn't get an image that did the effect justice.

The last two posts do shed some light on the subject though. Thanks all!
 
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