Calibrating two screens identical

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Calibrating two screens identical

I have an 24" iMac, about a year old, and a 2-3 yr old Eizo Flexscan L767 attached as a extra screen. I do a lot of photography, so want my screens calibrated.
I use a gretagMacbeth calibration gadget and Eye One software.
After calibration, my iMac screen still looks a lot brighter and more saturated then the Eizo screen.

I consulted a learned friend who suggested the following:

The reason (probably) your monitors look different is because each monitor requires a separate LUT (look up table) to hold the profile you make for it. Once both monitors are properly profiled they should be very similar. LUT’s are provided by your graphics card. Some only have one, some have two. One is more common, especially the built in graphics cards..

The most important thing to find out is does your graphics card have two LUT’s? Maybe you can look this up or ask Mac support? And if not lets look into what graphic card will. Chances are you can use the current graphics card for one monitor (built in monitor) and just get a inexpensive secondary card for your EIZO.<
End of first quote.

I am not a techie, so wonder if anyone can tell me here if my card supports 2 LUTs?

My card is : ATI Radeon HD 2600 Pro:

Full details at the end of this post.

further comment from my friend:

<div class="jive-quote">The problems I’ve had with ATI cards is the driver support. Always issues. Then I went to Nvidia which is mostly a gaming card, but it has excellent drivers. No more issues. I put in one 7950GT card.. discovered it only had one LUT (even though it had two DVI outs), so I got another and now I run two graphics cards. . Same model/series graphics cards, same model/series monitors. I use the second DVI to run non-color profiled devices like my 50” HDTV (for family slide shows) and DLP projector.<</div>

So if my Ati has only one LUT, is it possible to replace it with one that supports 2 LUT, OR can i add another one?

In terms of my service options, I live in Thailand, bought my iMac in Bangkok, and have it serviced there. But since I know and understand little of Graphics cards and LUT's, passing on this issue to a service person with limited english may be a problem.

iMac 24" - 2.4 Intl Core Due, Mac OS X (10.5.3), 3 Gb 667 Mhz DDR2 SDRAM ATI Radeon HD 2600 Pro:

Posted on Jul 15, 2008 4:13 AM

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Answer 1

Jul 16, 2008 10:14 AM in response to Kees5

I have a 20" iMac, and an external 20" screen. For calibration I use a Pantone Huey Pro, which is designed to handle two monitors. The Huey produces two profiles (look-up tables) that I can see if I go to System Preferences / Display / Color. Before I had the Huey I could have completely different color spaces on the two monitors, that they can be brought together means that the graphics card can display more than one setting at a time.

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Answer 2

Kees5 Author

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Jul 17, 2008 3:20 AM in response to Nicholas Brawne

Thanks a lot Nicholas,

As you may have guessed, I am a bit technologically challenged. I looked it up, and my screens have separate and different profiles. I also had advice elsewhere to NOT use the 'easy' option when calibrating, but a more comprehensive one offered by the EyeOne software. I'll do that first and see where it takes me.
Still wondering whether upgrading to the GeForce 8800 GS w 512MB, if available here would improve my system. I cannot presently buy a PowerMac, a new printer would have priority.

Anyone here installed (or had installed) an upgraded graphic card on a iMac 24"?

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Answer 3

Jul 17, 2008 1:23 PM in response to Kees5

I think you said that you are a photographer. For 2D applications like Photoshop that are processor intensive a better graphics card will have no effect. One of the downsides of the iMac is that it is not easily upgradeable.

Because it is so hard to get an exact color match between monitors I would do all your critical color adjustments on the iMac, and use the second screen for reference materials, palettes, finder windows etc.

Use the easy option for setting up your monitors, and put your money into a good printer.

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Answer 4

Kees5 Author

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Jul 18, 2008 3:49 AM in response to Nicholas Brawne

I'd love to use the iMac as my critical colour screen, but cannot. When i calibrate it using the EyeOne sensor and software, the iMac doesn't allow me to manually choose the settings i need to act as a good photo printer. I cannot adjust luminance, and it ends up with a luminance of about 1.94, when my preferred luminance for Photoshop and Lightroom adjustments is .90- 1.20.

Most good monitors allow manual adjustments. My Eiko has it, my old Sony CRT had it. Usually using a set of pushbuttons on the front. iMac doesn't have these and only seems to offer the automatic calibration through its own software, but without using a sensor to measure the values on the screen.

I maybe wrong and simply not have found the controls yet, but if I am right and they simply can't be accessed by users, this whole machine would actually be much less useful for photographers then I thought when I bought it.

Anyone else come across this issue?

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Answer 5

Kees5 Author

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Jul 18, 2008 4:17 AM in response to Kees5

I just did what i should have done a few days ago, and read the history of this board back a few pages, found many others complaining of the same problem, and a suggested solution, downloaded 'Shades' and installed it. It may fix my problem.
I'll now re-calibrate my screen, using 'easy mode' but lower luminance, simply by manually adjusting screen brightness to same level as my Eiko screen. Should be able to do that manually, or maybe using a lightmeter reading. We'll see if it gives me the desired outcome.

thanks guys

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Answer 6

Jul 19, 2008 9:44 PM in response to Kees5

Yes this has been gone over but you did good by reading back. For real critical calibration that you are expecting you would need something like an Eizo, Lacie or Nec 2690 monitor, which run somewhere in the $$$ neighborhood staring about 1200.00. Shades etal are O.K. but do not allow your whites to be correct as it acts in photo terms like a neutral density filter so you lower brightness but contrast suffers.

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Answer 7

Kees5 Author

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Jul 22, 2008 11:27 PM in response to pete mark

Thanks Pete,

I have an Eizo so will have to use that.

I spoke to my Apple dealer a few days ago, and he said that, contrary to what Nicholas wrote above, the Graphics card does NOT support two different LookUpLists. Two computer will give them different names, but when you look at the two profiles it produces, you will see that the numbers are actually mostly the same. Except for two strings of ASCII code, but they are likely to represent text identifying the monitor. I assume that unless I tell my computer which specific profile to use, it will choose the last one, which means that if today the last screen profiled is the iMac screen, my Eizo will also display according to the iMac calibration. This may well be a good explanation for some uneven printing I have been experiencing lately.

Sometimes I wonder if it wouldn't be useful if actual Apple tech staff would have an input in this board, as tech staff on other brand related boards sometimes have.

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Answer 8

ontop

Level 1

29 points

Aug 9, 2008 8:37 AM in response to Kees5

While reading your post:
I needed two monitors to have the same calibration...
I found a apple script in the colorsync files inside Library/Colorsync.
...Use calibration from other monitor...
And guess what? They look the same now!

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