Dell U2412M

[Sailor_Moon]

Not only that but the blue primary was 46% too bright and could not be corrected!

These values have to be taken with care. HCFR - unfortunately just like many many other programms in the TV sector too- assumes a fixed whitepoint (in this case the "mythical" D65 although there is nothing like the correct whitepoint) instead of the actual whitepoint (it is only used for normalisation here). Chromatic adaptations are also not carried out. All transformations are of course wrong if this whitepoint isn't achieved. In this case the actual whitepoint is near enough but the correct (= linear behaviour) luminance component is determined by the actual primary colors too (HCFR just uses the sRGB primaries relative to D65 as reference). I will calculate it on basis of your measurement data but almost certainly everything is correct.



Best regards

Denis

 

[Snowdog]

The gamut on mine was like PRAD's (possibly worse):

But, PRAD's and tftcentral monitors don't have the luminance problem with blue, so I may have got a dud panel.

TFTCentral is now using an i1 Pro spectrophotometer to measure primaries and there results show very close match to sRGB primaries. Certainly not off enough to be detectable by eye.

http://www.tftcentral.co.uk/reviews/content/dell_u2412m.htm#colour
"analysed using an X-rite i1 Pro spectrophotometer combined with LaCie's Blue Eye Pro software suite. An NEC branded and customised X-rite i1 Display 2 colorimeter was also used to verify the black point and contrast ratio since the i1 Pro is less reliable at the darker end.

The CIE diagram on the left confirms that the monitors colour gamut (black triangle) very closely matches the sRGB colour space (orange triangle). It extends a little past the sRGB space in greens in this 2D view of gamut but is a little short in reds."

 

[Sailor_Moon]

So here are the results for the shown graph:

Target Y- component normalized:

Red: 0,225
Green: 0,67
Blue: 0,105

=> 0,105 * 121,788 = 12,79 cd/m² for blue vs. 12,862 cd/m² measured.

Everything is just perfect. As I said: HCFRs calculation is based on sRGB primaries relative to D65 - but that doesn't represent the actual display state. So there is no nonlinearity (which would be problematic). That's one of the reasons why we are using our own solution (a simple profile validation is also not adequate apart from tools like the UDACT).

If one wants to (re)calculate self, here's the simple matrix calculation (Abbildung 3):
http://www.prad.de/new/monitore/specials/farbmetrik/farbmetrik-teil3.html

Best regards

Denis

 

[XoR]

The gamut on mine was like PRAD's (possibly worse):

measurements aside: is this difference in blue visible by naked eye?
it should be more cyan from where it is on this diagram than on say ordinary CCFL panel or normal CRT.

Not only that but the blue primary was 46% too bright and could not be corrected!

does it looks like there is blue tinge everywhere or just measurements show it?
I had BenQ LED-VA and immediately it was apparent blue is off (actually all colors were off, blue just seemed to be everywhere even when I decreased it's levels...) and unfortunately no calibration could help. Same is with all those cheap or not so cheap LED TNs - just hopeless case...

It's the best image to evaluate colors in such cases

Currently deciding whether to roll the dice and order another one.

Get another one, and if it's just monitor thing then you should return it if you don't like it immediately. From experience I know if first impression is bad then IT IS BAD (like LED-VA I was mentioning before - I exchanged it first and then tried to like it but failed...)

ps. I see you have good proble. If you create normal ICC file with calibration and profiling please post it here so we can evaluate it more precisely

 

[Sailor_Moon]

does it looks like there is blue tinge everywhere or just measurements show it?

Get another one, and if it's just monitor thing then you should return it if you don't like it immediately.

The measurements don't show a blue color cast but a correct and linear behaviour. If HCFR shows "0%" as "deltaLuma" in this scenario the screen would behave unusable nonlinear.

sonic_blues measurement data reflects our measurement quite exactly. Here is his data (black volume) after adaptation to D50 and transformation to Lab in comparision to sRGB (white volume). sRGB coverage about 93% just as we have measured.

sonic_blues data (posting 1000) in Lab (D50) along luminance axis:

Best regards

Denis

 

[10e]

wow, so negativity from saying that this monitor is only 93% sRGB and I like wide-gamut for it's versatility...

you people feeling good?

No, the negativity is based on your mixed and poorly "evolving" message. Next time make it clear what you are saying and instead of "93% sRGB gamut coverage is uncorrectable flaw" say "Is this standard/sRGB or wide gamut?"

See how much easier and clearer that is? Even one of the best affordable pro-sumer sRGB screens (LCD2490WUXi-BK) "only" had 95% coverage, and I haven't heard anyone on DP Review that uses it for sRGB photo work complaining about it.

 

[sonic_blue]

measurements aside: is this difference in blue visible by naked eye?

does it looks like there is blue tinge everywhere or just measurements show it?

Yes it was quite obvious that the blues were too bright (OS graphics, images I'm familiar with & RGB ramp).

ps. I see you have good proble. If you create normal ICC file with calibration and profiling please post it here so we can evaluate it more precisely

Here is the profile
http://www.mediafire.com/download.php?345d96wcga82o41

ColorHCFR .chc files I posted on page 32.

These values have to be taken with care. HCFR - unfortunately just like many many other programms in the TV sector too- assumes a fixed whitepoint (in this case the "mythical" D65 although there is nothing like the correct whitepoint) instead of the actual whitepoint (it is only used for normalisation here). Chromatic adaptations are also not carried out. All transformations are of course wrong if this whitepoint isn't achieved. In this case the actual whitepoint is near enough but the correct (= linear behaviour) luminance component is determined by the actual primary colors too (HCFR just uses the sRGB primaries relative to D65 as reference). I will calculate it on basis of your measurement data but almost certainly everything is correct.



Best regards

Denis

I will have to re-read over your posts to fully understand what you are saying, but in the meantime my understanding of sRGB is that the Y of the blue primary should be 7.22% of the Y of white (in my case 121.7cd/m2). So the Y of blue should be 8.7cd/m2 , but on mine it measured 12.8cd/m2 which is 46% higher.

 

[sonic_blue]

I had BenQ LED-VA and immediately it was apparent blue is off (actually all colors were off, blue just seemed to be everywhere even when I decreased it's levels...) and unfortunately no calibration could help. Same is with all those cheap or not so cheap LED TNs - just hopeless case...

Colour accuracy was actually very good on my Benq BL2400PT (charts here). The screen uniformity however was not so good (gamma shift on left side of the screen).

 

[sonic_blue]

As I said: HCFRs calculation is based on sRGB primaries relative to D65 - but that doesn't represent the actual display state.

But my display state is D65! Why should my blue Y target be 10.5% if my white point is D65? Shouldn't it be 7.22% for D65 white point? Or are you calculating the Y target for the pre-calibrated white point of my U2412 which was nowhere near D65?

Also, when I change the target white point in HCFR it changes the target Y of the primaries and secondaries too. So it would appear HCFR is calculating it correctly.

 

[elo408]

Here's my U2412m:

.

My u2412m looks just like his. I cant tell if i should return or not. I cant understand the difference between glow and bleed.

 

[10e]

Glow will go away as you move back and view the panel from a slightly further distance, bleed will stay.

You move back, view the panel straight on and not from an angle and look for bright spots. Bleed will sometimes be along the bottom, top or sides, where glow will always start to creep in from the corners as you move closer.

Also glow will move with your head. If you look at a corner close up and see no glow, then it's not backlight bleed.

 

[XoR]

gamut from icc from tftcentral

gamut of your monitor

something is off here with blue and green. Red is actually better with your measurements

 

[Sailor_Moon]

But my display state is D65!

That is correct.

Why should my blue Y target be 10.5% if my white point is D65? Shouldn't it be 7.22% for D65 white point?

Because your primaries don't reach sRGB relativ to D65. And that's the reference for HCFR and its "deltaLuma" information. As I said: Your display would be unusable nonlinear if you would achieve "0%" with the actual state. The relationship is quite easy: All primaries with full luminance must lead to white. So you can calculate the "right" luminance component from the xy chromaticity coordinates of primaries + white (see link in #1003).

Your display shows no problems and behaves like intended and like our sample. The color space is just not bigger but absolutely within the expectations for the used backlight.

Or are you calculating the Y target for the pre-calibrated white point of my U2412

No.

something is off here with blue and green

Without knowing more details about the profilation (e.g. chromatic adaptation) a very exact comparison is difficult. Under well defined conditions sonic_blues display behaves (regarding color gamut) identically to our display (see #1005). Of course there will some absolute error because of probe beeing used (white LED spectrum vs. CCFL spectrum) but the results are quite consistent in this case.

Best regards

Denis

 

[sonic_blue]

Because your primaries don't reach sRGB relativ to D65. And that's the reference for HCFR and its "deltaLuma" information.

So in other words, because the blue primary is a bit undersaturated and off hue, the luminance should be higher to compensate? Would that be correct?

 

[Sailor_Moon]

So in other words, because the blue primary is a bit undersaturated and off hue, the luminance should be higher to compensate? Would that be correct?

That goes in the right direction but I wouldn't call it "compensate". We know:

Chromaticity coordinates of red, green and blue
Chromaticity coordinates of white
red + green + blue = white

So there is only one luminance portion for each color that fulfils that relation:

Best regards

Denis

 

[sonic_blue]

The relationship is quite easy: All primaries with full luminance must lead to white. So you can calculate the "right" luminance component from the xy chromaticity coordinates of primaries + white (see link in #1003).

What if we had a 3D colour management system at our disposal, and we reduced the blue primary luminance without affecting the white point? Wouldn't this improve the DE for blue?

btw you can reduce the blue luminance on the 2412 without affecting white point by switching to Multimedia picture mode. However I found the red luminance becomes worse in that mode.

 

[Sailor_Moon]

What if we had a 3D colour management system at our disposal, and we reduced the blue primary luminance without affecting the white point? Wouldn't this improve the DE for blue?

Yes but the introduced nonlinearity would degrade the presentation enormously. You couldn't even make a valid matrix ICC profile representing the actual display state (the profilation software would force normalize the measured values).

Best regards

Denis

 

[sonic_blue]

Yes but the introduced nonlinearity would degrade the presentation enormously.

I'm struggling to think of why that would be the case. As long as you've got 255 shades of blue tracking perceptually uniform Y from 0-255, then where is the nonlinearity occuring?

When I calibrate Samsung TV's, I use the colour management system to adjust the primaries and secondaries. Are you saying that if I reduce the luminance of a colour to meet its target, that I am actually degrading the image?

 

[Sailor_Moon]

I'm struggling to think of why that would be the case.

We have a self emitting device (display) with 3 primary colors. A linear behaviour of these components is essential. Precondition is that max.intensity of red + green + blue add up to white. As described there is only one "solution" for such an interleaved system based on the current state.

When I calibrate Samsung TV's, I use the colour management system to adjust the primaries and secondaries. Are you saying that if I reduce the luminance of a colour to meet its target, that I am actually degrading the image?

You "just" have to be *very* careful. Unfortunately many programms in the TV calibration sector have a questionable colorimetric implementation regarding some important aspects like the whitepoint handling. The "safe zone" is small. Best example is HCFR which can only be reasonable used if your display is exactly calibrated to D65 white (the "D65 legend" is quite widespread). If you want to rely on the "deltaLuma" information you must even exactly achieve the reference chromaticity values.

Regarding "full featured" CMS systems with control over brightness, hue and saturation. Of course you must also adjust the luminance component - but you should do it with respect to linearity. If you can achieve the sRGB chromaticity values and D65 white exactly, the portions 0.2126 (red), 0.7152 (green), and 0.0722 (blue) are correct.

Best regards

Denis

 

[sonic_blue]

We have a self emitting device (display) with 3 primary colors. A linear behaviour of these components is essential. Precondition is that max.intensity of red + green + blue add up to white. As described there is only one "solution" for such an interleaved system based on the current state.

I understand that if we alter xy of blue then we must then alter Y in order to ensure equal amounts of RGB produce white. But what I don't understand is why we can't just reduce the Y of blue only for colours that contain blue (i.e everything in the monitor's LUT that contains blue but *not* equal amounts of RGB, in order to preserve the white point).

So the effect would be a blue primary that still has the xy error (since the gamut is limitation of the physical panel & backlight) but no Y error. Why would this be worse than having an xy error *and* and Y error?

Also it is clear to me that blues are overcooked on the U2412 in Standard/Custom Colour mode.

 

[Sailor_Moon]

But what I don't understand is why we can't just reduce the Y of blue only for colours that contain blue

Because the whole display state is "mixed up" then. We have an interleaved system. Linear behaviour is absolute fundamental. A nonlinear state is nothing you want to achieve (and isn't, as I said, covered by the ICC workflow => The resulting profile wouldn't describe the actual display state* because the software would have to force normalize the values - at least when using matrix profiles).

Why would this be worse than having an xy error *and* and Y error?

Because of the described "interleaving". An unpredictable system is very problematic and you would altogether deteriorate the accuracy. Unfortunately I'm reaching the limit of my wealth of expression. But I think a follow up in german wouldn't be helpful ;-).

Best regards

Denis

*
A good example is the DELL U2410 in custom color mode which shows such a nonlinear behaviour

 

[sonic_blue]

Because the whole display state is "mixed up" then. We have an interleaved system. Linear behaviour is absolute fundamental.

Say you have the colour RGB [0,0,128]. On the Dell, this colour is appearing too brightly, yes or no? Would you benefit from reducing the Y of this colour? I believe that you would.

The problem seems to be that Y of blue is pumped up to make R+G+B=D65, but then the Y of blue colours are too bright as a result. Do you agree?

 

[Sailor_Moon]

Say you have the colour RGB [0,0,128]. On the Dell, this colour is appearing too brightly, yes or no?

The RGB value has no "grounding" (which it gets through a designated color space including gradation). But that isn't connected with the problem we are discussing.

On the Dell, this colour is appearing too brightly, yes or no?

The brightess output in midtones depends on the gradation. But the brightness of your color sample will be "intrinsic correct" (see above) regarding the state of the DELL. If you want a most correct representation regarding whatever content you must use the display in a managed workflow. The CMM will then carry out the appropriate transformations (including gamut mapping if necessary). But the approach of minimizing the distance to an arbitrary aim by destroying overall linearity doesn't help. It will "destruct" the representation as a whole.


Best regards

Denis

 

[sonic_blue]

The RGB value has no "grounding" (which it gets through a designated color space including gradation).

The "grounding" would be the appearance of RGB [0,0,128] on a perfectly accurate sRGB monitor. If the U2412 is showing that colour undersaturated and 46% brighter than the sRGB monitor, then I can't see why reducing the blue brightness wouldn't bring it more into line with the sRGB monitor. Unless you are saying that it's preferable to compensate for the U2412's undersaturated blue by increasing its luminance by 46%. Judging by the overcooked look of blues on the U2412, I can't imagine that being the case.

 

[bensen]

When doing an exchange, do I send it back then they send me a new one or do they send a new one right away and bill for the new lcd and credit back when they receive the returned lcd?

Are there actually any with no blacklight bleed at all? Or all has some sort of bleed just how severe? The bottom right patch glows white on mine when I watch movies with dark scenes, which is a bit annoying.

 

[Sailor_Moon]

then I can't see why reducing the blue brightness wouldn't bring it more into line with the sRGB monitor

Because you are "screwing" the whole presentation over the tonal range of the screen - which is, especially in a workflow without color management (where thick LUT profiles can rescue at least some things), dependent on a linear behaviour (not referring to a Gamma of 1.0 of course). Unfortunately I'm, as mentioned, not able to describe the situation better in english - and a very technical description in german like in our special (but you could have a look at the first picture which shows a fresh profile validation of a nonlinear picture mode (Asus PA246Q user mode)) won't be very helpful I think.

No offense: It's of course up to you how to use and configure your screens. Maybe it helps to imagine how the additive mixture of colours works and also how transformations (at least backward and forward from and to the PCS) in a managed workflow are carried out by a CMM on basis of matrix profiles. It could also be helpful to look at the color space emulations of high-end screens which of course always preserve linearity after typing in whitepoint and primary chromaticity coordinates (they don't even have an option for the luminance component because of the implicit coherence => if I would type in your measurement values from the HCFR chart I would get your luminance values, including the "+46% blue").

then I can't see why reducing the blue brightness wouldn't bring it more into line with the sRGB monitor

The sRGB color space defines of course a linear behaviour regarding to its parameters (primary colors + gradation).

Best regards

Denis

 

[XoR]

Colour accuracy was actually very good on my Benq BL2400PT (charts here). The screen uniformity however was not so good (gamma shift on left side of the screen).

Those BenQ have misplaced RGB coordinates and so their gamut is strange too...

As is seen here (and much more when you look at those panel directly!!!) there are more intense yellows and violets and green is different too, more yellowish. Those colors are far beyond sRGB but those panels lack some colors like cyan and normal greens so it's not really wide-gamut, more wacky-gamut

Even very wide-gamut panel like U2410 cant display such yellows and violets

Interesting colors, yellow seem so over-saturated sometimes you could taste lemons But seriously, those panels had nothing to do with either sRGB or any standard...

 

[sonic_blue]

-deleted-

 

[sonic_blue]

But seriously, those panels had nothing to do with either sRGB or any standard...

Must have been a bad panel. You can see on my BL2400PT the gamut was very good, greyscale and gamma too. Panel uniformity and ghosting were my only issues with that monitor. It's screen coating was excellent, no grain at all

 

[genegold99]

When doing an exchange, do I send it back then they send me a new one or do they send a new one right away and bill for the new lcd and credit back when they receive the returned lcd?

Call them up to get the details. I once turned down an exchange, but part of the guarantee is advance eschange, i.e., to send you out one first so you're not left without a monitor. I imagine they put a hold on for the amount on your credit card and you have to return a monitor within a certain time to get it removed, or they charge.

 

[palaciav]

Call them up to get the details. I once turned down an exchange, but part of the guarantee is advance eschange, i.e., to send you out one first so you're not left without a monitor. I imagine they put a hold on for the amount on your credit card and you have to return a monitor within a certain time to get it removed, or they charge.

This has been my experience with Dell Small Business for work. Parts were overnighted, and the return sticker in the package was for overnight delivery as well. After about 4 days they will send you an email reminder, and you might get phone calls every other day as well until they either have the defective item or charge you.

Of course, with how many of these lolang's rep intimated they were shipping, it likely won't be overnight replacement.

 

[bern43]

When doing an exchange, do I send it back then they send me a new one or do they send a new one right away and bill for the new lcd and credit back when they receive the returned lcd?

Are there actually any with no blacklight bleed at all? Or all has some sort of bleed just how severe? The bottom right patch glows white on mine when I watch movies with dark scenes, which is a bit annoying.

Check the back of your packing slip/invoice. It has all the details on how to exchange. They'll send you one and then you have 10 days to return the old one. How long have you used the monitor? Mine had some backlight bleed the first night I used it, but it already seems to be getting better. I'd give it a few days if you haven't already and then check again.

 

[sblantipodi]

Mine had some backlight bleed the first night I used it, but it already seems to be getting better. I'd give it a few days if you haven't already and then check again.

Never heard about an "improvable" backlight bleed, do you mean that you used to the bleed?

 

[bern43]

Never heard about an "improvable" backlight bleed, do you mean that you used to the bleed?

Well maybe my eyes are playing tricks on me and I am just getting used to it, but it does seem better.

 

[albovin]

This is a very well known thing.
Post-assembly mechanical tension (the main cause of BL uniformity imperfections) decreases as the panel "exercises" (warming<>cooling).
Minor issues can vanish completely.

 

[william_fontaine]

This is now down to $329 - http://accessories.us.dell.com/sna/productdetail.aspx?c=us&cs=04&l=en&sku=320-2676

 

[slagcoin]

...

 

[Theodoric]

A bit OT, perhaps, but when does Dell's 100% satisfaction period kick in? When they ship it, or when it's delivered? The reason I ask is that mine is supposed to be here on Monday, but I live directly in the path of hurricane Irene and delivery may be delayed for a while depending on how bad the roads are. It may get here on Monday for all I know, but if it took an extra week I wouldn't be surprised either.

Yo, from chatting with Lolang's rep, I learned that the return period is 21 days from the day that you receive it, not the day it's shipped or the order is placed. Thanks Lolang, btw!

I bought the HP zr22w a while ago after I decided I couldn't afford the zr24w, but I'm yearning now for the 16:10 format and extra size. The LED backlighting, weight, size and apparent better black levels have made the U2412M the best decision for an upgrade.

Although my zr22w came with no dead pixels and minimal backlight bleed on the top, I do remember being somewhat dissappointed by the black levels and contrast, especially in low light movie scenes. I can only assume the zr24w is the same, but bigger.

Since I'll have both at the same place at the same time, if anyone wants me to run certain tests to compare them, or simply give an uneducated opinion about the contrast difference, etc., I'll see what I can do.

 

[dukenuke88]

hey guys I'll be joining the club soon...I just put in my order for the U2412m

I still haven't read through this thread...but I am active over at the U3011 thread, since I have one myself....is there anything I should be looking out for on the U2412M?

 

[10e]

hey guys I'll be joining the club soon...I just put in my order for the U2412m

I still haven't read through this thread...but I am active over at the U3011 thread, since I have one myself....is there anything I should be looking out for on the U2412M?

So far the only panel quality issues are some back-light bleed, and potential yellowish tint on whites, but for the most part it's been pretty good. Mine has no white/yellow tinting and the back light bleed I noticed at the beginning is basically (if not completely) gone.

If your U3011 is anything like my 3008WFP you'll likely notice the IPS glow is a bit "whiter" on the U2412M than the U3011, but otherwise it should be a good addition.

One thing to note is because the U2412M is sRGB it will be closer to the sRGB preset on your screen than the Adobe RGB or "custom color" mode.

Post up and let us know what you think when you get it.

Cheers!