# Colormunki calibrates my monitors to what?



## TexasPilot (Jun 22, 2016)

Good Morning:

I have started doing more printing of my photos.  After suggestions from some members of the Capture San Antonio Photographers Group I started using Costco.  After some hugely disappointing results I learned about ICC profiles, how to export my files using the ICC profiles for my local Costco printer (downloaded from drycreekphoto.com).  Better prints.  Then I learned about Colormunki. "Calibrated" both monitors with Colormunki Display.  Even better prints - especially poster-sized.

Here is my question. * Colormunki calibrates my monitor to "what?"  *I see it going thru the through the colors and adjusting, but to what objective color standard is the software makings its "decisions?"  Is it "matching" my monitor colors to my X-Rite ColorChecker Passport?  

I am certainly happy with the results, but would like to know more about what is going on in the process?

Thanks in advance for feedback and help.

Ed
San Antonio, TX 78218


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## DGStinner (Jun 22, 2016)

My understanding is that the software is telling the monitor to display, for example, 255,0,0 (pure red).  The Colormunki then detects the actual values being displayed.  After going through the different colors, the profile is created.


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## Johan Elzenga (Jun 22, 2016)

AFAIK, the software does two things; calibration and making a profile. Calibration is making sure that the monitor displays colors 'properly', so grey is really grey. Depending on the monitor, it may ask you to change some hardware settings to do that. And it will create a color lookup table that is loaded at startup. After the monitor has been calibrated, the profile will be created so that color-managed applications can use it to correct the RGB data of the images they send to the monitor.


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## Conrad Chavez (Jun 22, 2016)

TexasPilot said:


> Here is my question. * Colormunki calibrates my monitor to "what?"  *I see it going thru the through the colors and adjusting, but to what objective color standard is the software makings its "decisions?"


In the ColorMunki Photo software that I have, the first step is to choose the Easy or Advanced mode. If you choose Easy mode, it will just profile the device without telling you the details.

But if you choose Advanced, now you can see what objective color standard it is profiling to. You set the standard by choosing the White Point and Luminance. There are multiple choices for each of those, depending on what kind of work you're doing. A photographer editing for prints in a home studio might choose a D65 white point and a luminance of 120 cd/m2 (or lower), while a prepress operator who corrects to match contract proofs in a darkened room might choose a D50 white point and a luminance of 100 cd/m2.

Additional color standard options are in the ColorMunki Preferences, like the Tone Response Curve and the ICC profile version.

After you set up all of that and tell it to start, all of the tests it runs will use your settings as the reference that it will try to match, to the best of the display's ability.

I'm not sure what it is profiling to in Easy mode, but I wouldn't be surprised if it's a D65 white point at a luminance level of 120 cd/m2.


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## happycranker (Jun 23, 2016)

If you use the easy mode in the Colormunki the settings are D65 100 cd/m2 for laptop and 120 cd/m2 for LCD monitors.


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## LouieSherwin (Jun 28, 2016)

Let me add the following to the above information.  When given a unique RGB value each hardware device that uses RBG values to display or print colors will create a slightly different color. This is because of the physical differences between these devices and the methods used to display colors, LEDs, paper and ink, etc.. These variations especially between display (emissive media) and print (reflective media) can be quite noticeable. 

To handle this problem software engineers came up with the color management system (CMS) which part of your OS. In order for the CMS to work it has to know about the colors for each device. These are called color profiles. The ColorMunki device and software will send a set of RBG values to your monitor and then measure the actual color and creates a profile that describes your specific monitors colors. The same is true for the Dry Creek profile for your CostCo printer. Without going into detail the CMS uses these profiles to make sure that the colors that you see on your monitor as you edit your photo will look the same as the colors on your final print from Costo. 

-louie


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## Ian Hutchinson (Jul 10, 2016)

Louie, that is one of the simplest and best explanations I have ever read about colour calibration.


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