Wednesday, December 17, 2008

Calibrating Monitors with the Eye-One LT
including dual monitors and dual LUTs

I've spent the last four years staring at two monitors side by side that do not have matching colors. After a while, a minor irritant turned into a major irritant, and I bought the X-Rite Eye-One LT (aka the i1) to fix the problem.

As numerous others have noticed, the documentation leaves a great deal to be desired, so here is my addendum.

1. Don't bother installing from the CD. It's all out of date. Install the latest versions of the software from:

The only software required for calibration is i1Match, which is Vista-compatible as of v3.6.2. (You do not need to install the download labeled 32 & 64-Bit Drivers for Win2000, XP, and Vista. The drivers are included with i1Match)

2. Install the software before you plug in the USB cord. The manual is wrong when it says to do it the other way around.

3. Understand what your monitor is capable of. For the purposes of calibration, there are three classes of LCD monitors:

  • Monitors that do not allow you to adjust the contrast or whitepoint. My 5-year old Samsung 191T fell into this category. Eye-One works with these monitors, but the results are suboptimal. In general, it is almost impossible to calibrate these older monitors to be the same as other monitors.
  • Monitors that allow you to manually adjust the contrast, whitepoint, or RGB values. i1 walks you through making adjustments. The quality of the result depends on the number of adjustments available on the monitor.
  • Newer monitors where Eye-One is able to automatically control the monitor to set contrast, RGB and whitepoint. Such monitors are the easiest to calibrate and will have the highest level of success. Note that Eye-One only has built-in support for automatically controlling a small number of monitors. For other monitors, you'll need to manually make the adjustments.

4. Ambient light matters. The ambient light in your room has a significant impact on the result. Make sure you calibrate your monitor in the light where it's normally used. Don't do what I did and calibrate your monitor at night when the room is lit up with incandescent bulbs. The result is not satisfactory. (Note that the i1Match software actually warned me about this when I turned on "measure ambient light". The measurement bars shows that the light in my room was inappropriate for successful color correction.)

If you have Vista, you may also run into the problem of your color correction settings being lost every few minutes. Install Vista Service Pack 1.

5. Run the calibration. This is generally fairly painless. Make sure you read the help panel on the right in i1Match - it has useful information. Make sure you do the Contrast adjustment, if i1Match asks you to.

If you are calibrating an LCD monitor, you should use the counterweight instead of the suction cups built into the sensor. I found that the suction cups wouldn't stick to the matte screen of my LCD monitor.

6. Understand LUTs. The LUT, or "LookUp Table," is a feature of your video card that automatically performs color correction at all times. Without a video LUT, color correction only works in software like Photoshop and PaintShop Pro that can perform software-based color correction. Virtually all video cards made in recent years contain a hardware LUT.

You can verify that your video card has LUT support by downloading the LUT Tester.

When you run color calibration software such as i1Match, the result is an ICC file. ICC stands for Internation Color Consortium. The file contains information on how RGB values need to be adjusted to display properly on your monitor.

Here's the annoying part. Windows, even Windows Vista, does not understand how to load the hardware LUT with the ICC file. So Windows has all of the infrastructure to track ICC profiles for each monitor, but Windows doesn't actually do anything with that information!

The solution is software that loads the LUT when Windows starts. Such software reads the ICC profile for each monitor and loads the appropriate LUT. The most common example is Adobe Gamma Loader, but the Eye-One includes the Logo Calibration Loader, which should always be used to load the LUTs.

7. Dual monitors and Dual LUTs. This one is the 900-pound gorilla. The problem with dual monitors is that you need dual LUTs. Every monitor requires a unique calibration, even two monitors that are the identical model. Many video cards today have connections for two monitors. In order to show the correct colors in both of them, each must be calibrated separately AND your video card(s) must have one LUT for each monitor. Most low-end video cards (and most pre-2006 video cards) only have a single LUT, which means that either you need a second video card for your second monitor or you need to upgrade to a card with dual outputs and dual LUTs.

It can be tricky to determine if your system will be able to calibrate two monitors. There are several variables:

  • Operating system: If you are running Windows Vista SP1, then the OS includes the required support. If you are running Windows XP, then you need to install extra software.
  • Eye-One software. The i1Display 2 software apparently has built-in support for multiple monitors. The i1Display LT software does not support multiple monitors, but see my workaround below.
  • Dual LUTs. To determine whether your video card has dual LUTs, run through the calibration on the primary monitor. On the final screen, use the Calibration On/Off button to see how calibration affects your monitor. If you have dual LUTs, then only the primary monitor will be affected by the Calibration On/Off button. If you only have a single LUT, then both monitors will be affected.

I have verified that the Logo Calibration Loader supports multiple LUTs. It is intelligent enough to read the ICC profile for each monitor and set the appropriate LUT.

My system has an nVidia 7950GT video card. I was very happy to discover that this card has dual LUTs.

8. Remove conflicting software. When you install i1Match, your Startup group is updated to include the Logo Calibration Loader. This sofware updates the LUT(s)in your video card. Unfortunately, there are several other applications that try to do the same thing and must be removed. The most common is the Adobe Gamma Loader, which is installed with PhotoShop.

9 Advanced users. If you want to know more about what your monitor can do, download and the free sofware HCFR. Although this software will not create or manipulate ICC profiles, it will give you copious information about ambient light, your monitor's color space, and more. Just be prepared to spend some time figuring how it works. You'll also need to copy EyeOne.dll into HCFR's installation directory. Make sure you enable Eye-One support in HCFR.

10 Finding your ICC profiles in Vista. The ICC profiles are managed by Windows. To view them in Vista, go to Control Panel | Color Management. Note that this information is maintained on a per-monitor basis and you can switch between monitors using the droplist at the top of the window. Important! If you change the default ICC profile for a monitor, you'll notice that your screen colors do not change. You must run the Logo Calibration Loader to update your LUTs after you change the ICC profile. You can run this Loader from the Start menu or from C:\Program Files\GretagMacbeth\i1\Eye-One Match 3\CalibrationLoader\CalibrationLoader.exe.

11 Calibrating your second monitor with Eye-One LT. The cheaper LT version of Eye-One does not include built-in support for multiple monitors, but the workaround is easy. (This is for Vista, I haven't tested this in XP.) This process assumes that you have already completed the calibration for your primary monitor and that you've verified that you have dual LUTs. Here is how to calibrate your second monitor:
  • Open Control Panel
  • Open Personalization
  • Open Display Settings
  • Left-click the big #2.
  • Check the box labeled "This is my main monitor."
  • Left-click the big #1.
  • Uncheck the box labeled "Extend the desktop onto this monitor."
  • Click Apply
  • Your primary monitor is now disabled. You should be able to run i1Match and calibrate the second monitor without difficulty. The ICC profile for the second monitor will be set to the new ICC profile and the ICC profile for the first monitor should be unchanged.
  • Reenable your primary monitor by reversing the steps above for the "big #1" and the "big #2."
  • Run the Logo Calibration Loader to reload the LUTs for both monitors. This step is required.

Other Thoughts

I'm quite happy with my Eye-One. It calibrated my desktop PC, my laptop, and my Mac. It's considered to be the best colorimeter on the market that's "affordable." (The Spyder hardware also appears to score well, but Amazon Reviews are littered with complaints about their software.)

Another alternative is the Huey, which is half the price of the Eye-One. However, the Huey cannot calibrate luminence, which is critical for calibrating today's excessively bright LCD monitors. Also, luminence calibration is required in dual monitor setups to make both monitors appear the same.

After final calibration, I was not able to get good results calibrating my Samsung 191T or 191T+. However, both of these monitors are over four years old, both have over 15,000 hours on their backlights, and neither has an adjustable whitepoint. So the poor results are to be expected. (Both monitors looked better after calibration than before calibration, so there was definite improvement.) On the other hand, my brand new HP 2475w ended up with near-perfect calibration. After creating the ICC profile and loading the LUTs with Eye-One, I switched to HCFR to graph the results and the results were excellent. Luminance was a perfect match to theoretical and RGB was corrected within 5% for all values.

[Update 2/25/2009] I tested the latest version of i1Match (3.6.2) under Windows 7 Beta and it worked correctly. The Logo Calibration Loader also worked. One small hiccup was that it couldn't find the position of the sensor, but I just told it to continue and it worked fine.

[Update 5/21/2009] I upgraded the T42/p from Win7 Beta to Win7 RC. I copied the color profile from the Beta to the RC, set it to be the default, and the screen magically updated - even though I didn't start Logo Calibration Loader. This means that, as of Windows 7, Windows finally includes support for automatically loading the LUTs based on the color profile. Great news! (This means that you can remove the the Logo Calibration Loader from your Startup group if you have Windows 7.) Note that I was not able to test dual monitors to see if Windows 7 could handle multiple LUTs.


  1. Thank you for this excellent and comprehensive article, which is easily the best analysis I've seen on the subject.
    I'm not yet sure if my Radeon 4850 card supports dual LUTs - experimentation needed.
    Have you tried the x-rite DisplayProfile.exe utility? It's on the Eye-One CD. I'd be interested in your views on it.

  2. This article was exactly what I was looking for. I'm using an Eye-one Display2 and NVidia 7950 video card as well. Using your instructions, I was able to setup dual monitors on Vista 64. This was verified with the DisplayProfile.exe utility on the Display2 install disk. When the DisplayProfile window is open, simply move it back-and-forth between screens and the installed ICC profile is displayed. Very cool! I would add that the iMatch Software installs the separate LUTs tables on the video card, so there is nothing that needs to be done in Vista Color Management. The profiles are there -- leave it alone. Thanks again. Now I'm enjoying great color on BOTH monitors.

  3. Great article. I'm anxiously awaiting my new monitor today, and will try your technique for calibrating it with my old one. Thanks for putting in the time to educate us in a clear and easy-to-digest style.

  4. Thank you my friend for the dual monitor knowledge as it relates to the i1. Your documentation is much appreciated and helped me get setup quickly. Without your write up this would have been a frustrating experience. Cheers, Matthew
    --EQUIPMENT: Gateway FPD2485W, Samsung T260N dual monitors with the i1 Display2 and Nvidia GeForce 7300 LE---

  5. Thanks so much for your great post.

    I have three HP LP2475w monitors and would love to calibrate all three, but I'm wondering if I will only notice the results of the calibration in color managed applications. If after calibration, all images/graphics in the OS and color aware internet browsers are displayed more "correctly", then I'd be more inclined to get one graphics card per monitor, but if loading a separate ICC profile for each monitor will only make a difference in color managed applications like Photoshop, then I might just choose a single card solution with one LUT such as the new ATI 5000 series. The new ATI cards support 3 monitors, and as well, there is the ability to group all the monitors into one large panel with the eyefinity software. Any help would be greatly appreciated.


  6. davem1979 - Not sure if you read everything I wrote? I covered your questions in detail in Steps #6 and #7. Once you've loaded the LUT, the change affects all applications. That's the point of doing color correction in hardware instead of in software.

    As to whether you can use one card or need multiple, the answer depends on whether the ATI 5000 series has multiple LUTs. I expect that it would.

  7. Hi Jim, Thanks so much for your reply.

    I think your expectation is correct. I just spoke with ATI GPU support, and they told me that the new 5000 series cards have 3 DACs with 3 LUTs, so they should load 3 separate ICC profiles for each monitor attached. He mentioned that the older generation ATI cards supported Dual LUTs, and now the new generation cards are moving forward with that in mind. I guess I'll just have to try the graphics card and find out. I'll keep you posted...

  8. You rock!!! Thanks for the detailed review.

  9. Hello Jim, thank you for very interesting article. Recently I bought two Hp LP2475w screens and at the beginning I was terrified with oversaturated colors (some of them, mostly red, pink and green). I asked at few forums about this issue and received answers suggesting calibrating screens. So I bought EYE One Display 2 calibrator. It calibrated screens well. I've got natural colors in PS and Firefox. Unfortunately all other programs and desktop is still oversaturated. I went thru calibration process finished succesfully with two ICC profiles applied to system, CalibrationLoader.exe is running in background, there is no any other calibration software loaded and still I have proper colors only in few apps. I understood from your article that I should get proper colors in all system (Vista Business 32bit). Am I right?
    Kind Regards.....Rafal

  10. Anonymous,

    You didn't say which version of Windows you are running, but if you are running, Windows 7, the ICC profile is applied automatically and Calibration Loader is not needed.

    I would make sure that the calibration profile is really being applied. Both PS and Firefox support doing ICC handling on their own, so it almost sounds like it's being applied in software, not hardware.

    Also, did you disable the Adobe Gamma Loader?

    Hope this helps.

  11. Hello Jim, thank you for quick reply. I use Vista Business 32bit. The ICC profiles created by Eye One Display 2 were automatically applied to monitors ICC profiles. I checked it in Color Management window, Device tab - both screens are using new ICC files. Maybe it has something to do with Advanced tab. At the beginning, before I bought calibrator I was playing around with options trying to solve the problem. Here is screengrab of current setting: Do you know what file should be selected Device profile field?
    I removed Adobe Gamma Loader from Startup and to be sure I even changed extension of this file to exe1. Now in Startup folder I've got Logo Calibration Loader. I also started it manulally: C:\Program Files\GretagMacbeth\i1\Eye-One Match 3\CalibrationLoader. There is no difference. Interesting thing - I can't find this file in Window Task Manager > Processes Window, but maybe it won't be visible there. I have no idea what else I can do to get proper colors in system. I would be grateful for any suggestions. Regards.....Rafal

  12. Thank you for the informative article.. It was really helpful!

    However, I am stil having great difficulty getting consistent colour representation between my monitor display and my print output after calibration, so wondering if you can assist?

    I recently purchased Dell U2410 monitor, and have used XRite's Eye-One Match3 to calibrate my monitor (using the Custom preset, with gain of 87, 79 and 89 for the RGB values respectively. Brightness set to 1, Contrast set to 99).

    I use Adobe Lightroom 3 to edit and print my photos, and I notice the output is sigificanty darker, which I expected, but also has a strong yellow colour cast. As lightroom is colour managed, and I have used the manufacturer's (Canon) printer profile and recommended ink and paper, I think the issue is due to my monitor calibration, which appear to have been lost upon start up, or perhaps my graphics card driver is overriding the ICC profile changes.

    I am using Windows Vista SP2, and my graphics card is nVidia GeForce 8400M GS, driver version Judging from online forums, there could be a number of factors causing the calibration to be lost. I am quite confused just trying to understand it all?

    To complicate the matter further, I notice nVidia Control Pannel had the "Adjust Desktop Color Settings" with non-blank values. They are as the following:
    Brightness: 42%
    Digital Vibrance: 0%
    Contrast: 2%

    Should I set all the above values to zero prior to calibration? Or are they the default values already?

    Thank you..


  13. Hi Susan,

    The Eye-One is going work with however nVidia is set. So the only question is whether the nVidia control panel is set in set a way as to cause a problem. You can use HFCR to see what your color space looks like. Certainly your monitor should be up to the task.

    For the printer, I don't have any advice for you. Monitors are additive color, printers are subtractive, so the entire meaning of "matched colors" is a little fuzzy in the first place. My graphic design friends tell me that color matching printers is an expertise all in itself.