Bad uniformity

[maciek]

So do we just have to live with it? It seems so, since it's impossible to get a decent panel, and the bigger they get the worse it gets.

I got the LG 34UM95 lately, and of course, the luminance uniformity was bad on the big portion of left side of the screen.
I was lucky enough to return it since in EU countries they don't have to let you return something you've used.

So i bought the NEC PA272W, and as a supposed high end screen it's far from it.
The luminance uniformity is ok, the white point is not.

This is with uniformity compensation set to maximum, i could live with the luminance, but the white point uniformity looks bad there's a noticable red cast in the bottom corners.
Now i can't even return it and i have to waste my time and go through warranty - fixing process as if it was my fault the monitor was rubbish.

Here's an interesting thing, the NEC comes with a display report, the uniformity test ignores 10% of each of the monitor's side, furthermore they cranked the uniformity compensation to the maximum for the test.

So basically they produce mediocre panels and use maximum uniformity compensation so they pass the test. That feature should not be used to their advantage, it should be used for monitors which passed the test without it but still don't look perfect.

 

[spacediver]

that's pretty good luminance uniformity.

Hard to make sense of the chromaticity uniformity, as Kelvin's aren't really that meaningful in this context. x,y or better yet delta E's would give a better idea of how bad it is.

The uniformity from this review looks pretty good.

Do you notice these issues when using the display for regular stuff?

 

[maciek]

that's pretty good luminance uniformity.

Hard to make sense of the chromaticity uniformity, as Kelvin's aren't really that meaningful in this context. x,y or better yet delta E's would give a better idea of how bad it is.

The uniformity from this review looks pretty good.

Do you notice these issues when using the display for regular stuff?

Well it made sense to me since my target was 6500K and this way i could see how much off i was.

I don't notice it when editing photos, the cast doesn't reach that far but i can see it on the application's UI, when browsing, it's mostly noticeable on bright neutral elements than darker ones.
My start menu icon is also supposed to be white, and it's noticeably reddish.

 

[flod]

Well it made sense to me since my target was 6500K and this way i could see how much off i was.

not all 6500k are equal. you can have a greenish display, which is terribly off target, still show up to have 6500k correlated color temperature. this is why color temperature, though something we may have developed intuition for, isn't a great way to describe the magnitude of color differences.

for example if i ask you what size your phone is, and you tell me that it is 7mm thick, that doesn't say much as i have no information about its length or width.

in the same way, correlated color temperature is only a one dimensional measure of a color's hue... to characterize a particular color's hue you need two numbers.

to quantify the difference between two colors, it's not as simple as taking the euclidean distance between the two numbers of the two colors and considerable research has been done to develop formulas for measuring color differences: http://en.wikipedia.org/wiki/Color_difference

that is what is meant by deltaE or dE.

 

[spacediver]

what flood said. Read this link:

http://www.pro-lite.uk.com/File/colour_temp.php

Your target isn't 6500 K (or, more, precisely, 6504 K), but D65.

 

[ArtMarshall]

This is with uniformity compensation set to maximum, i could live with the luminance, but the white point uniformity looks bad there's a noticable red cast in the bottom corners.
Now i can't even return it and i have to waste my time and go through warranty - fixing process as if it was my fault the monitor was rubbish.

What country do you live in? Warranty service should be fairly simple if the problem is measurable.What color sensor are you using for the measurements?

Here's an interesting thing, the NEC comes with a display report, the uniformity test ignores 10% of each of the monitor's side, furthermore they cranked the uniformity compensation to the maximum for the test.

So basically they produce mediocre panels and use maximum uniformity compensation so they pass the test. That feature should not be used to their advantage, it should be used for monitors which passed the test without it but still don't look perfect.

Unfortunately this is the case with all LCD panels. Even though we have a quality standard for our panels from the panel manufacturer, we have developed the Digital Uniformity Compensation to improve upon the limits that exist with LCD panel quality. We measure with the uniformity on so that you can see the best that your display can perform.

I hope that this helps.

 

[maciek]

what flood said. Read this link:

http://www.pro-lite.uk.com/File/colour_temp.php

Your target isn't 6500 K (or, more, precisely, 6504 K), but D65.

Thanks!

What country do you live in? Warranty service should be fairly simple if the problem is measurable.What color sensor are you using for the measurements?

I live in Poland. I'm using Spyder 4 Pro. Well i can either send it to the service, or the store, but either way it can take up to a month to get it fixed...

Unfortunately this is the case with all LCD panels. Even though we have a quality standard for our panels from the panel manufacturer, we have developed the Digital Uniformity Compensation to improve upon the limits that exist with LCD panel quality. We measure with the uniformity on so that you can see the best that your display can perform.

I hope that this helps.

I don't really blame NEC and i know it's a common problem, i'm just disappointed not even in NEC but all monitor manufacturers because they seem to be more concerned about cramming in more pixels.

I used the P232W before i got this one and it was much better, it was nearly perfect but with this one i now regret i didn't go with Eizo.

 

[ArtMarshall]

I live in Poland. I'm using Spyder 4 Pro. Well i can either send it to the service, or the store, but either way it can take up to a month to get it fixed...

Ah, sorry. I'm not as familiar with our service process in Poland. I would expect Spyder 4 to pick up a good, correct dE with the right software.

I don't really blame NEC and i know it's a common problem, i'm just disappointed not even in NEC but all monitor manufacturers because they seem to be more concerned about cramming in more pixels.

I used the P232W before i got this one and it was much better, it was nearly perfect but with this one i now regret i didn't go with Eizo.

I understand your frustration. I would suggest contacting the NEC support for Poland and see what your options are for support.

 

[maciek]

Ah, sorry. I'm not as familiar with our service process in Poland. I would expect Spyder 4 to pick up a good, correct dE with the right software.


I understand your frustration. I would suggest contacting the NEC support for Poland and see what your options are for support.

I have contacted them and they said i can send it but it might be within the norms.
Once i get another monitor to use i'll send this one to them.

 

[maciek]

Here's a better uniformity test done with agryll for anyone interested.

 

[spacediver]

I still don't see any chromaticity measurements or delta E's...

 

[maciek]

I still don't see any chromaticity measurements or delta E's...

It shows chroma difference from the reference (center), to do dE i'll have to use agryll's spotread, i'll try later.