No matter what the contrast is set to, the ghosting is still extremely obvious. ChrisM: In the PixPerAn while running the chase test, set the first two RGB values to 255/255/255 and set the third to 51/51/51 and you will see what I mean. No matter what the monitor values are, the ghosting is still very very obvious. I reset my monitor to factory settings before testing this as well.

Chris:


I'm using OS X, where the "display contents while moving" option is invalid. The issue is still there. I've tried different color calibrations within OS X, and the problem still exists. A color profile is not going to fix the problem, in my opinion (although it would be nice to have one available for Mac users). Once I can find a place to host videos I made I will link them.


I agree that it's a hardware issue, perhaps not "timing", but rather an "overshoot" and response time issue. With factory defaults, it seems like the RGB values are pushed as high as they will go. I don't know if this is to achieve contrast or what, but if you go into the custom and turn the RGB values to below 93 or so, the problem is mitigated. So the pixels aren't being driven as "hard" (how do these settings physically affect the monitor? Lower voltages across the pixels?). I think the higher settings are pushing the pixels into saturation and therefore causing undesired results. Since these extreme settings are default with the monitor, it makes me think that they are an attempt to pad the specs of the monitor.


I believe it has nothing to do with computer software and everything to do with the controller of the monitor. Default settings may achieve better brightness/contrast specs (which seem to be the new fad in LCD's, rather than response time), but cause reduced performance otherwise.


Thoughts?

can you test a theory for me? Can you switch the screen to a lower resolution (1024 x 768 or something) and up the refresh rate from 60Hz to 75hz? You may need to use Powerstrip or something, or create a custom resolution to allow this, but see if you can run / force the screen at 75Hz for a bit. You prob can't do this at the full 1920 x 1200 res though.

Then see if this helps eliminate / reduces the black ghosting at all? In theory running the screen outside it's optimum refresh rate of 60Hz can impact the overdrive application of the panel, and so this might reduce the overshoot artefacts people are seeing

give it a go if you can and let us know :)

Message Edited by Baddass on 09-06-2007 10:24 AM

Chris:

No I tried that a few days ago, there was no difference whatsoever.

I honestly think it's a timing issue as mentioned in the Anand posting and that other post I added to the thread yesterday. The actual color settings on the monitor don't appear to help at all.

MitchellD_, If it were a timing issue, why wasn't the ghosting issue (not the trailing) seen on the 2407WFP? It has the same response time specs as the 2407WFP-HC? Response Time 6 ms typical (Grey to Grey) / 16 ms typical (Black to White) Hmmm...


The panel has been updated slightly though hasn't it to the new LTM240CS01 S-PVA panel from Samsung? Also CCFL backlighting updated to HighColour. It SOUNDS like the problem is related to the overdrive control, with some pretty bad overshoot in dark tones being seen....it's not uncommon on some other Samsung models (using Samsung panels that is) like the Samsung 940BF for instance. Users found very bad ghosting from the overdrive, and resorted to turning the RTA function off (through OSD) to fix / remove it. Maybe if the overdrive impulse was selectable through the OSD that would help solve it?

Thats my reason for asking about the 60hz vs 75Hz as above, since running at 75Hz might force the overdrive impulse to be adversely affected.

Message Edited by Baddass on 09-06-2007 10:21 AM

I indeed too remember that I've read about complains about certain Samsung monitors displaying the same issue (the dark ghosting that is, since I think some people still confusing like 3 issues with eachother). I tried lowering the heat inside the monitor with putting a (pretty powerful) ventilator next to it, but it didnt seem to reduce the dark ghosting (altho the monitor felt cooler). So what else changes inside the monitor after you let the monitor on for a while (the dark ghosting doesnt appear right after you turn the pc and monitor on, but after less than 30 minutes), beside its getting hotter?

And maybe the differences between the HC and non-HC version are big enough not to compare them with eachother (and therefor not use the same settings and configurations for it)? This can be the problem too (using a non-HC setting on the HC and that causes the issues).

O and I dont know if this is posted already but: Moving windows (with content shown) over the top blue/green bar of MSN live (latest version)main and chat window seem to leave a bright white ghosting behind. Easy to reproduce and spot, but not sure to which issue this is related (cant seem to 'calibrate it away' btw).

O, and 60 vs 75hz: problems still appear the same on 1280x1024 @ 75hz.

Message Edited by Guno on 09-06-2007 10:43 AM

also the issue has been documented here:

http://www.tftcentral.co.uk/articles/dell_2407wfp-hc.htm

covers the issue, and contains all the most relevant info, fix suggestions etc. handy for those who cant be bothered to scour the thread and all over the net :)

Message Edited by Baddass on 09-06-2007 10:24 AM

MitchellD_,

If it were a timing issue, why wasn't the ghosting issue (not the trailing) seen on the 2407WFP? It has the same response time specs as the 2407WFP-HC?

Response Time 6 ms typical (Grey to Grey) / 16 ms typical (Black to White)

Hmmm...

Bravo Baddass, on the excellent interpretation of the issue - I hope that this helps ChrisM's lab guys pin down the problem. :)

Mitch

---

@Baddass wrote:
thanks for checking the 75Hz, was worth a try as i know it impacts RTC on some models.


Regarding the time the screen is left on....if the issue is related to the RTC / overdrive control as it appears, then it's an overshoot issue where the liquid crystals are forced to make a larger change in orientation than they really need to. This is the principal behind overdrive really, since an extra high voltage is applied to boost the LC's into a new orientation faster, often by going past their required state / orientation and relying on the smaller "fall time" to quickly get back to the desired state.

So in this instance, the LC's are trying to change to a dark colour (seems to happen on dark backgrounds from what i can tell) from a light colour, but are overshooting to an even darker (even black) colour where they have aligned themselves too far. I would imagine that this is more pronounced once the panel has been on a little while and everything has "warmed up". trying to explain that in a crude and simple way so people can follow. hope it makes sense :)

---

EE's FTW! Exactly what I was trying to say earlier...