Profiling Overhead Displays

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This reserved article originally appeared in CHROMiX ColorNews Issue 12 on April 26, 2004.

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by Steve Upton


Calibration & Profiling of Overhead Display Systems

Can it be done?

Yes in fact, it can. With the right equipment and software you can calibrate and profile your overhead display system. It makes a considerable difference as well. Neutrals look neutral, correct saturation stops your images from looking washed out or artificially punchy. The hues of important colors like logos also look correct. This is especially important if your presentation includes your client's logo and other corporate colors.

What is a Beamer?

In North America a "beamer" is what yuppies call their BMW. In Europe a "beamer" is the common nickname for an overhead projector system. In Color Management a Beamer is an overhead calibration system from GretagMacbeth. As far as we have been able to determine, it is the only overhead display calibration and profiling solution offered on the market today.

How does it work?

Well, it is similar to calibrating your monitor with a little more setup. Basically you connect your computer to the overhead display projector and set it up like normal. Make sure you have the contrast and brightness set the way you like and the image is clear and stable. Then you attach the Eye-One spectrophotometer to a small stand that allows you to aim it at your overhead system's screen. A small white dot appears on the screen allowing you to fine-tune the spectro's positioning. Then the calibration and profiling proceeds in a similar (if somewhat larger) fashion to monitor calibration.

Is it just the same as a monitor?

Pretty much, yes. Just like your monitor, the curves in your computer's graphic card are adjusted until the screen shows the desired white point and gamma. Then an additional series of colors is measured to build a profile characterizing the system. The calibration curves are embedded into the profile and it is saved and set as your system's profile. All this is just like a conventional display profile.

What does it help?

As mentioned above, it neutralizes neutrals, calibrates white point and gamma and, when an application uses the profile, helps display correct hues & saturation. From a bigger-picture perspective, it helps you make your point. It makes your image more professional and your competitors wonder what they're missing.

Can I calibrate/profile once and use it across multiple systems?

Not typically. Just like a conventional monitor, calibration and profiling of a display system involves the display AND the graphics card in the CPU. The combination of the two is what's calibrated. The overhead display system will behave differently connected to a different CPU and so each combination needs to be calibrated separately. This is one of the first questions we typically hear. If the CPUs are very similar (like the same model PowerBook, for instance) then you may get away with it. In most cases however, it's time to re-calibrate.

What about my system display vs the overhead display?

If you have a monitor connected to your computer in addition to the overhead display then you may want each of them calibrated. You can calibrate & profile each if:

You can NOT calibrate & profile each if:

If you can't, calibrate the overhead and live with the other display looking a bit "off" while you present. Select your regular display profile when your presentation's over to return to normal (Windows systems will require a reboot to load the correct calibration tables).

How about DVD playback?

DVD player software is not color managed. That doesn't mean that calibration won't improve your display however. Setting a desirable white point, fixing the gamma curves of each RGB channel to 2.2 and nailing down your grays will all help raise the quality of your DVD playback.

What about Photoshop?

Photoshop and other applications that can use a display profile will go the extra step of ensuring that color hue and saturation will be as correct as display gamut will allow.

What about Presentation Software like PowerPoint and Safari?

That's a good question. If the presentation package is color aware like Safari, then you have no worries. It will color manage your images for great display quality. For PowerPoint users on Windows, GretagMacbeth includes a plug-in that allows the color management of images within your presentations. 
While it may seem like this is a product-specific article I really wanted to get the word out on color managing overhead presentation systems and the Beamer is really the only product we know that will do the job. If any readers know of additional tools that will do this function, please let us know.

Thanks for reading, Steve Upton

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