Profiling Devices for Monitors

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This reserved article originally appeared in CHROMiX ColorNews Issue 42 on July 7th, 2010.

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- an article by Patrick Herold


"I don't understand the differences between the Spyder, the i1 Display2 and the Colormunki. I have searched the Internet and I only get different opinions from different people about what works best on their own displays, or a manufacturer's claim that their puck is great. But all this business about colorimeters and spectrophotometers is really confusing. Can somebody explain the merits or drawbacks of each one?"


It wasn't too long ago that your choice of a piece of hardware for profiling your monitor was limited to two or three options, all of which would work pretty well. You final choice might depend on how much money you had, or what brand you had heard good things about.

With the entry of a few new models in the market, and especially the introduction of wide gamut displays, this question of 'what do I get to calibrate it?' is getting more complicated. Ideally, we like to take your emails and phone calls to the sales or technical support departments so we can give a good answer based on your individual setup. But we thought it would help a lot of people to give an overview of the basics of this subject here.

Spectrophotometers vs. Colorimeters

Calibration devices fall into two main camps: Spectrophotometers and colorimeters.

A spectrophotometer (i1Pro, ColorMunki) is designed to measure light energy at various frequencies across the entire spectrum of visible light. Its measurement returns data from roughly 400nm (nanometers) to 700nm or so. Basically, it measures many bands of light at once. These different bands of spectral data are brought together by the profiling software to identify individual colors. Spectrophotometers are able to measure reflective light (off of a page) as well as emissive light (off of a monitor) which is why many of these devices offer printer profiling abilities also. So this can be another point to consider when buying a device to calibrate your monitor: If you are interested in making your own printer profiles as well, consider a device that will do both.

A colorimeter (DTP-94, i1 Display 2, Spyder 2, Spyder 3) is a simpler device that makes use of filters to measure the intensity of red, green and blue. Measuring these primaries is roughly similar to how our eyes work, too. The filters reduce a broad range of light wavelengths into a few measurement values. Therefore, the accuracy and quality of these instruments depend a lot on the filters used - how durable they are over time, what colors they are specifically created to measure, and so forth.

Because spectrophotometers read a large number of bands, instead of just a few, they are considered to be more accurate than colorimeters. (They are also more expensive.) However, there is a major drawback. Because they read more bands of light, they will tend to introduce more noise into the mix. This is not much of a problem until you get down to measuring things like shadow detail and blacks. Imagine you're a spectrophotometer, dangling off the front of a display and you're asked to measure a black patch. Well, there won't be much of anything there to read, but you give it your best. You gather all the data from some 36 bands of wavelengths and because of digital noise and sensor dust, that will add to your report of how bright black is. For this reason, spectrophotometers tend to not measure shadow detail as dark as most colorimeters do. For example, the Monaco Optix (DTP-94) is famous for getting great shadow detail. It even has some noise-reduction circuitry built into it.

I'm starting to hear some of the gears in your mind start to work. You're already starting to make plans for what instrument you might buy next, depending on whether color accuracy or shadow detail is important to you. If it were only that simple!

Wide Gamut Displays

The monkey wrench in all of this is the wide gamut display. Suddenly, people are able to buy displays that produce much more saturated colors - in the range of the AdobeRGB gamut. It makes sense that a colorimeter developed before these wide gamut monitors came on the scene is not intended to measure more saturated colors. So some of these models, like the DTP-94, are not recommended for the newer displays. Some models, like the X-Rite i1 Display 2, were developed early on, but have been tested to also work fine on the newer displays. Some, like the Spyder 3, are newer and have been developed with the newer monitor gamuts in mind.

In many cases, a wide gamut monitor will come with a colorimeter that is a "re-branded" version of one of the models above. It has been specially tuned to work with the display for which it is intended. Some manufacturers believe this is the only way to ensure that accurate color is achieved without sacrificing shadow detail. HP, NEC, LaCie and Eizo all have colorimeters that they offer that are specially tuned to work with their high end displays and their own software.

LED displays

Another twist on this is the recent introduction of LED-backlit displays. They are another flavor of wide gamut display. In some cases, the LED's themselves can be adjusted to output specific white points. You would just about have to calibrate with a spectrophotometer in order to be sure of accurately capturing whatever colors are being put out by those models. On the other hand, the newest iMac uses an LED-backlit display with only a slightly larger gamut (10%) than the sRGB gamut. These should have no trouble being calibrated with a typical colorimeter.

If you have the more traditional monitor that resembles the sRGB spectrum, you will do fine with any of the colorimeters mentioned above. If you are getting one of the high end displays, it is best to get the colorimeter that is made for that display. If you have a variety of wide-gamut displays to calibrate, you should look into a spectrophotometer. If you have a wide-gamut display that does not have a custom-tuned colorimeter, then you should consider a spectrophotometer or one of the newer colorimeters. If you already have a colorimeter, it might work quite well with a wide gamut display, so it is worth a try to test it out before throwing it in the garbage. As I mentioned already, most colorimeters will tend to give you slightly better shadow detail than a spectrophotometer, so you have to keep that in mind while weighing your choices.

That's about it for general recommendations. There is a lot more that can be said for specific displays and profiling systems. CHROMiX sales and tech support personnel are familiar with all of these issues and can make more informed recommendations for your individual setup. Feel free to contact us for a no-obligation discussion of your profiling needs.

Thanks for reading,

Pat Herold



(Editor's note: New devices have come to market since this article was published. See the article Review of the DISCUS colorimeter and i1Display Pro blog entry for more information.)



Don't forget, you can discuss this article and anything else from this newsletter in ColorForums.com:

http://www.colorforums.com/viewforum.php?f=19

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