Technology Corner

by Julio Palleiro

The False Interpretation of the Image
Part II: Isn’t “The Calibrator” a movie starring the California Governor?

Not quite, but I can see that as an interesting avant-garde experiment.

When the shutter is snapped on any digital camera, the censor determines each pixels color. The camera almost never gets the color right. This is one of the pivotal tasks of a re-toucher. In many circumstances color accuracy for advertising layouts, gallery photographs, or magazine covers are equally or more important than popping pimples or applying digital makeup on a model. However, fixing color in Photoshop isn’t enough. Proper color takes preparation, starting with monitor calibration.

Monitors and printers are just like camera sensors. The monitor determines each pixels color based on a profile (covered in last months issue). Unfortunately for monitors and printers there is no universal profile that works for everyone. Most monitors and printer papers come with a generic profile, but hardware varies. Each model monitor and printer can produce radically different color even when using the same profile. In many cases this can happen with the EXACT model!

The solution for this is purchasing a calibrator. A calibrator is a device that works with its software to measure an array of colors and creates a profile. We at Rich Imaging use X-Rite’s Eye-One Photo.

Calibrate Good Times
Color temperature is measured in degrees Kelvin. The sun’s light is approximately 5600k, which is surprisingly blue light. A light bulb is around 3200k, which is orange/red. Weird, huh? We always think of bright light as being reddish, but if you know anything about science, blue flames are hotter than red ones. Okay, so what does this have to do with monitors? The color temperature is also measured in the same fashion; the user not the calibration system must determine this setting. If you are using an LCD monitor you should set your monitor at either 5000k or 6500k. You may see better results at the higher temperature.

Gamma 1.8 or 2.2
Sounds like a fraternity ranking of some sort. But don’t fret you won’t be hazed. Gamma correction is another option that the user must define before calibration. To explain gamma fully would require a lot of math talk since it is technically a formula. But we aren’t Rich Calculus, Inc. so I will stick to how it relates to imaging. Gamma creates contrast. It is a contrast correction that targets the mid-tones. All monitors and televisions have this setting, but many do not allow you to change it.

At one point there was ongoing debate between using a gamma of 1.8 or 2.2, the latter being contrastier. 1.8 was once an almost exclusive standard for Macintosh systems; however, this in no longer the case. Nowadays, Mac’s have become more inline with PC and industry standards, thus the 1.8 gamma is no longer a necessity only a rare preference.

It is also important to calibrate with your everyday lighting setup to ensure color accuracy for your viewing conditions. For the most part the calibration software does the rest for you. You should calibrate around once a month or so. Many professionals calibrate every week and some every day! But don’t go that far or else you may end up in Calibrators Anonymous.

One last and extremely important note on calibration, despite all of this work to finesse your monitor or printer, you will probably not match other calibrated systems. Why? Because people will use different calibrators, monitors, printers, paper, office/house lights. There are so many factors that alter color. Try to get it as close as possible and hope for the best.

And most importantly, if everyone calibrates their monitor, regardless of the gamma, color temperature or other options your calibration software may provide, then the entire industry will improve its workflow tremendously.

Leave feedfack as usual.

Next article: We will go more in depth on printing and proofing, exploring the differences between RGB prints, and the various types of CMYK proofs.

June 2008

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