How video calibration works
How video calibration works – and why you want it
by Brent Butterworth
I’ve spoken with many people who are shocked to learn they have to spend hundreds of dollars extra to have their theater’s video projector professionally calibrated. I can sympathize. After all, who among us hasn’t brought a brand-new TV home, plugged it in, turned it on, and never once touched the picture adjustments?
I can’t tell you a fancy calibration process is going to make The Biggest Loser any more captivating. But when you’re watching movies, accurate color reproduction and crisp detail draw really help draw you into the story, especially with a projection system. Achieving this level of performance is an incredibly complicated process for which most amateurs are no more qualified than they would be to do a brake job on their car.
The very first thing a calibration technician does is make sure your system is hooked up correctly. There’s a huge benefit here that doesn’t often get discussed—you can be sure all of your devices (Blu-ray player, cable box, etc.) are set for the optimum resolution for your projector. The tech’s also going to make sure the proper cables are used and that they’re all installed correctly. You can rest assured knowing you’re not one of the millions of people watching standard-definition video when they could be getting high definition.
Then the tech will check the physical installation of the TV, making sure that the screen is level and unobstructed. If it’s a projection system, the tech will check to see that the image is properly zoomed, centered, and focused.
Next, the tech will make basic adjustments to such controls as brightness, contrast, and sharpness, using either a special test DVD or a video signal generator.
Now comes the complicated part, where the tech adjusts the grayscale of the display. Grayscale is actually a function of the mix of red, green, and blue in the display. Get the mix right and you’ll get a perfectly neutral gray (or black or white), and all your other colors should fall into line, too. Get the mix wrong and the blacks, grays, and whites might look blue. Or they might look red. Or the blacks might look greenish while the whites look purple. This process takes anywhere from about 30 minutes to 2 hours, depending on how bad the TV looks at the start, and it involves test equipment costing $5,000 to $15,000.
On many newer TVs and projectors, the tech will be able to adjust the specific colors of red, green, and blue, to assure that the TV’s delivering the full range of color of which it’s capable.
There are other steps, too, and the more features manufacturers add to their TVs and projectors every year, the more things the calibration technician needs to check.
I’ve been through the calibration training program run by the Imaging Science Foundation three times, and I review projectors on a regular basis, yet I still find the calibration process complicated and challenging. Sure, if you’re really tech-savvy and wanted to invest in the necessary test gear, you could do the job yourself. But by the time you get good at it, you’ll probably be ready to buy a whole new display.
