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 Monitor: multiple OS (Linux and XP), calibration, sRGB, internal LUT
Author: La_Maudite 
Date:   11-28-07 07:39
Ha, double crap....

Crap 1: Mon Sony G500 m'a lache hier.
Crap 2: Je lis aujourd'hui que le moniteur que je considerais ne fait pas exactement ce que je pensais en sRGB.

Plutot que de reecrire le message que j'ai laisse sur http://www.dpreview.com , voici un lien suivi d'un cut-paste du texte:
http://forums.dpreview.com/forums/readflat.asp?forum=1004&thread=25797268

"Hi all,

My Sony G500 CRT just died on me yesterday. I had seen it coming, so I did some research on LCD panels a few months ago.
I was considering the NEC LCD2690WUXi-SV for many reasons:
- 26"
- Wide gamut
- Internal 12 bits LUT
- Good color accuracy
- Came with the software and hardware to calibrate the monitor

At the time, I saw just one negative point that I could live with:
- Refresh rate a bit slow for video and gaming.

Now that my monitor has died, I decided to look for new reviews and check for prices and availability in Canada. I was surprised to find in this forum (Thanks to everyone who wrote on the subject BTW! :-) that the 2690 can't be calibrated in sRGB mode, only in Adobe RGB.... Say what?
http://forums.dpreview.com/forums/readflat.asp?forum=1004&message=25098312
http://forums.dpreview.com/forums/readflat.asp?forum=1004&message=25399659&q=2690+srgb&qf=m
http://forums.dpreview.com/forums/readflat.asp?forum=1004&message=25058538&q=2690+lut&qf=m

Now, as others have mentioned in these threads, I don't understand why the LUT can't be used to calibrate the sRGB mode if one chooses to. But it looks like Adobe RGB is just the preferred mode and NEC decided not to provide the sRGB calibration for a reason that eludes me.

I'm glad I found out before buying, but that said I think I would have liked that monitor. Now, does it really matter that you can't calibrate in sRGB? It depends on what tools you're using. I mostly work in Linux, and as some of you might know, color management is abysmal, or should I say nonexistent in Linux. My goal of having a LUT stored internally was in part to be able to calibrate the monitor in XP and then use the calibrated monitor in Linux.

The other issue is that most applications are not color management aware in XP either. Of course, photoshop is, and some will say that Firefox 3.0 will also be ICC aware, but really, I think sRGB is he to stay. Don't get me wrong, having the possibility to use Adobe RGB is a good thing, but I think I would be using the sRGB mode most of the time.

So, here I am, looking for a monitor with an Internal LUT of more than 8bits that can be calibrated in sRGB mode. Is there such a thing?

I could of course buy a NEC LCD2690WUXi-SV anyway, and use it in sRGB for the time being, hoping for Linux to get up to speed with color management and Adobe RGB. My question then.... is the color accuracy good in sRGB? Having a 8bit LUT on the computer is out of the question for me."

Donc si vous avez des suggestions, s.v.p. repondre ici ou sur dpreview, a votre convenance.

 
 To wide-gamut, or not to wide gamut
Author: La_Maudite 
Date:   11-28-07 18:47
Bon, j'ai passe beaucoup trop de temps a lire la dessus aujourd'hui. Ma conclusion, c'est que les moniteurs wide-gamut ne sont pas souhatable sauf s'il est dedie a l'impression, ou encore qu'on utilise toutes des applications "color management aware" qui prendra en compte que le moniteur est en AdobeRGB et non pas sRGB (standard).

Je *pense* que le modele 24" de NEC ferait l'affaire, mais il reste un point nebuleux pour lequel j'ai pose la question sur dpreview (qui d'ailleurs est horriblement lent pour ce qui est des forums.... pleins de timeouts... sigh):
http://forums.dpreview.com/forums/read.asp?forum=1004&message=25805368

"Tom_Bruno wrote:
> Last week I took delivery of a NEC 2490WUXi.

Congrats on your purchase. Like you, I was going for a NEC 2690WUXi before reading this thread. So thank you very much for starting the thread and asking all the right questions, and of course thanks to everyone who contributed to this thread.

I now understand that the sRGB mode can't be calibrated and that the only way to use the 12 bits internal LUT is to use aRGB. Since I want to switch between Linux and XP, I want the colors to be accurate when using applications not color management aware. So the NEC 2690WUXi can't be a good option for me.

I read all the posts in this thread, and there is still one thing that isn't 100% clear for me. I think the NEC 2490WUXi makes possible the calibration in sRGB mode using the 12 bits internal LUT. Is it really the case??? It's not obvious from your last post, and I've read conflicting things about that. I just don't want that profile to be stored in the LUT on the graphics card.

In other words, if the standard sRGB profile is used in the by XP, does the calibration give good results? That would ensure that, when switching to Linux, the calibration would remain the same and the colors would be accurate for all applications.
What profile are you using right now in XP?

One last thing way to put it.... I want to calibrate the monitor, then connect it to a different computer and still have a calibrated monitor which is accurate for sRGB. Is it too much to ask? ;-)"

 
 Pas de "wide gamut" pour moi
Author: La_Maudite 
Date:   12-05-07 10:27
Je termine mon monologue.

Bien que j'ai surtout discute d'un modele en particulier (NEC 2490WUXi), je crois que ca s'applique a tous les moniteurs avec un "wide gamut" qui n'ont pas de 3D-LUT (lire ce qui suit pour savoir pourquoi). Voici donc un resume des discussions que j'ai eu sur dpreview, question de les archiver:

==============
http://forums.dpreview.com/forums/read.asp?forum=1004&message=25805368
Forum PC Talk
Subject Re: NEC 2490WUXi rocks! sRGB looks great.
Posted by Carl Robitaille [CLICK FOR PROFILE]
Date/Time 10:34:27 PM, Wednesday, November 28, 2007 (GMT)

Tom_Bruno wrote:
> Last week I took delivery of a NEC 2490WUXi.

Congrats on your purchase. Like you, I was going for a NEC 2690WUXi before reading this thread. So thank you very much for starting the thread and asking all the right questions, and of course thanks to everyone who contributed to this thread.

I now understand that the sRGB mode can't be calibrated and that the only way to use the 12 bits internal LUT is to use aRGB. Since I want to switch between Linux and XP, I want the colors to be accurate when using applications not color management aware. So the NEC 2690WUXi can't be a good option for me.

I read all the posts in this thread, and there is still one thing that isn't 100% clear for me. I think the NEC 2490WUXi makes possible the calibration in sRGB mode using the 12 bits internal LUT. Is it really the case??? It's not obvious from your last post, and I've read conflicting things about that. I just don't want that profile to be stored in the LUT on the graphics card.

In other words, if the standard sRGB profile is used in the by XP, does the calibration give good results? That would ensure that, when switching to Linux, the calibration would remain the same and the colors would be accurate for all applications.
What profile are you using right now in XP?

One last thing way to put it.... I want to calibrate the monitor, then connect it to a different computer and still have a calibrated monitor which is accurate for sRGB. Is it too much to ask? ;-)
==============
==============
http://forums.dpreview.com/forums/read.asp?forum=1004&message=25814602
Forum PC Talk
Subject Re: NEC 2490WUXi rocks! sRGB looks great.
Posted by Will49 [CLICK FOR PROFILE]
Date/Time 3:01:55 PM, Thursday, November 29, 2007 (GMT)

Carl Robitaille wrote:
> I read all the posts in this thread, and there is still one thing
> that isn't 100% clear for me. I think the NEC 2490WUXi makes possible
> the calibration in sRGB mode using the 12 bits internal LUT. Is it
> really the case??? It's not obvious from your last post, and I've
> read conflicting things about that. I just don't want that profile
> to be stored in the LUT on the graphics card.

The sRGB mode is not calibratable on either models (it's a factory preset). However since the 2490 is basically an sRGB gamut monitor, you can calibrate the monitor in it's Programmable mode to sRGB's white point and gamma, and it will result in a "calibrated sRGB monitor".

> In other words, if the standard sRGB profile is used in the by XP,
> does the calibration give good results? That would ensure that, when
> switching to Linux, the calibration would remain the same and the
> colors would be accurate for all applications.

If your applications in Linux are all assuming an sRGB monitor, then yes this would pretty much work, even though you aren't able to install a color profile on Linux.
> One last thing way to put it.... I want to calibrate the monitor,
> then connect it to a different computer and still have a calibrated
> monitor which is accurate for sRGB. Is it too much to ask? ;-)

As long as you are using DVI (digital) video, then you can do this, since the calibration is stored in the display, not the video card. If you are using analog video you will have less accurate results.
See this thread for what to check:

http://forums.dpreview.com/forums/read.asp?forum=1004&message=25228409


--
Will Hollingworth
Manager of OEM Product Design & Development Engineering
NEC Display Solutions of America, Inc.
==============
==============
http://forums.dpreview.com/forums/read.asp?forum=1004&message=25815363
Forum PC Talk
Subject Re: NEC 2490WUXi rocks! sRGB looks great.
Posted by Carl Robitaille [CLICK FOR PROFILE]
Date/Time 4:21:54 PM, Thursday, November 29, 2007 (GMT)

Hi Will,

Thanks again for the great info you provide here.

Will49 wrote:
> The sRGB mode is not calibratable on either models (it's a factory
> preset). However since the 2490 is basically an sRGB gamut monitor,
> you can calibrate the monitor in it's Programmable mode to sRGB's
> white point and gamma, and it will result in a "calibrated sRGB
> monitor".

Cool, that's what I wanted.

> If your applications in Linux are all assuming an sRGB monitor, then
> yes this would pretty much work, even though you aren't able to
> install a color profile on Linux.

My understanding is that, if no profile is used (on Linux or otherwise), sRGB is the prefered choice so that the content is displayed correctly everywhere (w/o profile attached to the file of course).

I know it's not ideal for printing, and I would have gone for a wide gamut monitor if the sRGB mode was better. I'll consider one when color management is used in all the apps and OS I use. Until then, what I need is a calibrated sRGB monitor.
> As long as you are using DVI (digital) video, then you can do this,
> since the calibration is stored in the display, not the video card.
> If you are using analog video you will have less accurate results.

Great!

> http://forums.dpreview.com/forums/read.asp?forum=1004&message=25228409

Thanks for the link. For whatever reason, it didn't show up in my searches. I'll have one last question that I'll post in the other thread.
==============
==============
http://forums.dpreview.com/forums/read.asp?forum=1004&message=25815765
Forum PC Talk
Subject Re: 2690WUXi and LUTs (I wish Will from NEC would see this)
Posted by Carl Robitaille [CLICK FOR PROFILE]
Date/Time 4:41:32 PM, Thursday, November 29, 2007 (GMT)

Will49 wrote:
> Doing gamut mapping in a monitor to make it behave like it has a
> different (smaller) gamut than it actually has, requires very
> sophisticated 3D LUTs and transforms. Applying these transforms in
> the 2690 means that the LUTs are no longer available for use in
> calibrating the display with SpectraView.

That's what I don't understand. Is there a paper somewhere that I can read to understand what makes it complicated to do so? Without knowing the internal workings of the programmable LUT and SpectraView II, I think it's safe to say that the LUT is basically a mapping of 2^24 -> 2^36, mapping 8 bits RGB inputs to 12 bits RGB outputs. Since sRGB is essentially (totally?) a subset of aRGB, why can't the LUT be filled with colors matching sRGB (as close as possible of course) and using only a subset of the gamut available? Is it a software limitation like I think it is, or is there something more to it?
> If someone really needs to have an calibrated "true" sRGB display, I
> would recommend either going for the 2490, or using a standard LCD as
> a secondary display for proofing sRGB.

That's what I intend to do. But if the limitation is software, it's a shame that I'll have to "limit" myself and buy a 2490 instead of a 2690, which was my first choice.
==============
==============
http://forums.dpreview.com/forums/read.asp?forum=1004&message=25818131
Forum PC Talk
Subject Re: 2690WUXi and LUTs (I wish Will from NEC would see this)
Posted by Will49 [CLICK FOR PROFILE]
Date/Time 7:33:58 PM, Thursday, November 29, 2007 (GMT)

Carl Robitaille wrote:
> That's what I don't understand. Is there a paper somewhere that I can
> read to understand what makes it complicated to do so? Without
> knowing the internal workings of the programmable LUT and SpectraView
> II, I think it's safe to say that the LUT is basically a mapping of
> 2^24 -> 2^36, mapping 8 bits RGB inputs to 12 bits RGB outputs.

Not quite. It is three 1D (red, green and blue) 8 bit (2^8) in by 12 bit out (2^12) LUTs.

> sRGB is essentially (totally?) a subset of aRGB, why can't the LUT be
> filled with colors matching sRGB (as close as possible of course) and
> using only a subset of the gamut available?

Because 1D LUTs can't map colors in the way necessary to manipulate one gamut into another. That requires a 3D LUT or sophisticated dynamic color processor.
A true 12 bit 3D LUT would need (2^12)^3 = 68719476736 entries.


--
Will Hollingworth
Manager of OEM Product Design & Development Engineering
NEC Display Solutions of America, Inc.
==============
==============
http://forums.dpreview.com/forums/read.asp?forum=1004&message=25819216
Forum PC Talk
Subject Re: 2690WUXi and LUTs (I wish Will from NEC would see this)
Posted by Will49 [CLICK FOR PROFILE]
Date/Time 8:32:58 PM, Thursday, November 29, 2007 (GMT)

> A true 12 bit 3D LUT would need (2^12)^3 = 68719476736 entries.

I should clarify that an 8 bit in x 12 bit out 3D LUT would need (2^8)^3 = 16777216 12 bit values.
==============
==============
http://forums.dpreview.com/forums/read.asp?forum=1004&message=25819783
Forum PC Talk
Subject Re: 2690WUXi and LUTs (I wish Will from NEC would see this)
Posted by Carl Robitaille [CLICK FOR PROFILE]
Date/Time 9:23:27 PM, Thursday, November 29, 2007 (GMT)

Will49 wrote:
> Not quite. It is three 1D (red, green and blue) 8 bit (2^8) in by 12
> bit out (2^12) LUTs.

Got it.

> Because 1D LUTs can't map colors in the way necessary to manipulate
> one gamut into another. That requires a 3D LUT or sophisticated
> dynamic color processor.

Got it. Makes sense.

> A true 12 bit 3D LUT would need (2^12)^3 = 68719476736 entries.

I see that you clarified in your replay that it would take 2^24 entries of 12 bits each. That's not that too much memory nowadays. It seems to me that it's something you should consider in your furure line of high end monitors.

Thanks again for your time. It looks like it's I'm going to buy a 2490. All I need now is to find the SV version in stock somewhere in Canada.
==============
==============

 
 Re: Pas de "wide gamut" pour moi
Author: AirBete 
Date:   12-05-07 10:36
J'ai suivi ton monologue avec interet car je devrai magasiner un LCD bientot. Cependant, je dois admettre que je ne m'y connais pas du tout et que j'ai de la difficulte a bien comprendre les echanges que tu as recopies ici. Il faudra que tu m'en parles de vive voix j'imagine.

AB.

 
 Autres liens concernant le "wide gamut" et le sRGB
Author: La_Maudite 
Date:   12-05-07 10:47
D'autres liens a lire pour ceux qui considereraient acheter un moniteur "wide gamut".

Ces moniteurs ne sont pas a eliminer de votre liste d'achat necessairement, mais il faut savoir quels sont les compromis qui sont faits. Pour ma part, ne travaillant pas dans un environnement avec le "color management" totalement integre, il etait plus important d'avoir du sRGB bien calibre que du aRGB. Plus ne veut pas toujours dire mieux, et c'est le cas ici, du moins pour moi. Je suis bien content de l'avoir compris avant d'acheter mon moniteur. J'espere juste avoir bien compris ;-) Vous pourrez vous faire votre propre idee en lisant les liens suivants.

http://forums.dpreview.com/forums/readflat.asp?forum=1004&message=25415867
http://forums.dpreview.com/forums/readflat.asp?forum=1004&message=25399659
http://forums.dpreview.com/forums/read.asp?forum=1004&message=24998798
http://forums.dpreview.com/forums/readflat.asp?forum=1004&thread=25060360
http://forums.dpreview.com/forums/readflat.asp?forum=1004&message=25655370
http://www.hardforum.com/showthread.php?p=1031725700&highlight=2490#post1031725700
http://www.hardforum.com/showthread.php?p=1031503783&highlight=2490#post1031503783
http://www.outbackphoto.com/tforum/viewtopic.php?TopicID=1700

 
 Re: Pas de "wide gamut" pour moi
Author: La_Maudite 
Date:   12-07-07 10:11
AirBete wrote:
> J'ai suivi ton monologue avec interet car je devrai magasiner
> un LCD bientot.

Oui, je pense que tu es probablement le seul que ca peut interesser, ou du moins intriguer ;-)

> Cependant, je dois admettre que je ne m'y
> connais pas du tout et que j'ai de la difficulte a bien
> comprendre les echanges que tu as recopies ici.

En fait l'ideal serait peut-etre que je fasse un resume. C'est vrai que c'est pas evident de s'y retrouver, surtout qu'on n'est pas en mesure de tester les choses avant de les acheter. Grrrrrrr.

> Il faudra que
> tu m'en parles de vive voix j'imagine.

Ouaip. Je vais devoir aller a l'universite avant la fin de la session. Probablement au debut de la semaine prochaine. On pourra resumer tout ca de vive voix (pour finir par me rendre compte que je n'ai pas fait le bon choix j'imagine.... LOL).

 
 Re: Pas de "wide gamut" pour moi
Author: AirBete 
Date:   12-07-07 10:56
La_Maudite wrote:
> Oui, je pense que tu es probablement le seul que ca peut
> interesser, ou du moins intriguer ;-)

Mon moniteur, un Sony G500 (mouhahaha), est en train de me lacher aussi. C'est pour ca que ca m'interesse a court/moyen terme. Aussi, je me suis achete un LCD y'a deux ans pour le bureau et je le trouve tres bien "out of the box". C'est un Nec2170NX. J'ai fait une petite calibration tres approximative (i.e. a l'oeil, lol) en jouant avec la correction gamma de chaque composante RGB a partir du Control Center de KDE. Pour visualiser des photos, ca me parait suffisant. Pour faire de l'edition, il faudrait probablement que je sois plus precis et que je fasse la correction directement a partir du moniteur. C'est la que je nage dans le nebuleux.

> En fait l'ideal serait peut-etre que je fasse un resume.

Ce sont les enjeux surtout qui ne sont pas clairs pour moi. Quel est le probleme, qu'est-ce qui est souhaitable d'avoir, quelles sont les solutions possibles en ce moment (au niveau hardware et software) et pourquoi telle solution est-elle meilleure que telle autre pour un usage donne.

AB.

 
 Re: Pas de "wide gamut" pour moi
Author: La_Maudite 
Date:   12-07-07 11:01
AirBete wrote:
> Ce sont les enjeux surtout qui ne sont pas clairs pour moi.
> Quel est le probleme, qu'est-ce qui est souhaitable d'avoir,
> quelles sont les solutions possibles en ce moment (au niveau
> hardware et software) et pourquoi telle solution est-elle
> meilleure que telle autre pour un usage donne.

Ouaip, je te ferai un petit resume que je tenterai de garder le plus court et clair possible. Le probleme, c'est qu'il n'y a pas qu'un critere de selection, alors ca rend la discussion un peu moins... euh... lineaire a defaut de trouver un meilleur terme ;-)

 
 Re: Pas de "wide gamut" pour moi
Author: La_Maudite 
Date:   12-25-07 03:28
> > Because 1D LUTs can't map colors in the way necessary to
> manipulate
> > one gamut into another. That requires a 3D LUT or
> sophisticated
> > dynamic color processor.
>
> Got it. Makes sense.
>
> > A true 12 bit 3D LUT would need (2^12)^3 = 68719476736
> entries.
>
> I see that you clarified in your replay that it would take 2^24
> entries of 12 bits each. That's not that too much memory
> nowadays. It seems to me that it's something you should
> consider in your furure line of high end monitors.

Et bien il semblerait que dans un futur pas si lointain, il y aura des moniteurs qui l'offritont.... Evidemment, ca ne sera pas achetable au depart, mais ca va dans la bonne direction.


http://forums.dpreview.com/forums/read.asp?forum=1004&message=25606742
Forum PC Talk
Subject Eizo CG301W display
Posted by DavidC [CLICK FOR PROFILE]
Date/Time 12:26:25 AM, Wednesday, November 14, 2007 (GMT)

"This looks fantastic -

http://www.eizo.com/press/releases/pdf/CG301W_pr.pdf

- it can be hardware calibrated for both full gamut colour and sRGB.

No doubt it will cost the same as a small house - or even a small house with a swimming pool.
David
http://www.davidcolepictures.co.uk "

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