Weakest Link of Monitor Calibraiton
Surely everyone in graphics and photography knows the importance of a well calibrated monitor by now. But a well calibrated monitor is only as good as it’s weakest link. Let us discuss what can go wrong.
A proper calibration should take into account more than just the monitor itself. In fact, you should start with the room you work in. Lighting should be controlled in color temperature and brightness and preferably be indirect lighting. For example, bright windows in front or behind your work area can affect the color and brightness you perceive and will change as outside lighting changes. Bright overhead lighting can also glare on the screen or worse, directly into your line of site. Ideally you should have a good ambient light source that is at a good level for both your eyes and monitor and in a place that does not cause unwanted glares or stress to your eyes when doing color correction. A perfect space would also use color corrected lighting to reduce the effect that incandescent and standard florescent lights have on the way you see color.
Both at home and at the lab I work in a very dimly lit room (compare to a movie theater before the previews) and for screen to print matching, I use a color corrected light table near my screen that does not glare into my eyes or onto the screen itself. I also keep the light turned off when I am not making comparisons to prints. Just remember to allow any color corrected lights as well as your monitor warm up before making comparisons. The color and brightness changes as the tubes warm up to their normal operating temperatures. To further help glare, I use a purpose built monitor “hood” that can be purchased with some brands of high end displays. I personally use a LaCie 324 24″ wide gamut display with the included hood.
The colors around you can also influence your vision. This means no brightly colored walls, crazy colors on your desktop and even the clothes you wear may even slightly shift your perception. Your eyes will automatically want correct for whites and other known color which can greatly hinder any corrections you make.
Now that we have the room lighting and working conditions ideal, we can move on to the monitor and the calibration itself. First of all, before calibration you will need to be sure your display is ON and running for long enough to get up to normal working temperature which can take as long as a half hour. (I use the computer while I wait. This way it doesn’t go into screen saver mode, thus restarting my warm-up time.) This way the calibrations are not correcting for color shifts as the display warms up during the calibration process.
As for colorimeters, their are a number of tools available for professional calibration, some are more affordable than others. I have several including some older and some newer models. They all work in roughly the same way, mostly the software itself is what varies. My current favorite tool is the ColorMunki Photo from X-Rite. It can calibrate LCD monitors, projection screens and it has the ability to calibrate your printer as well. (More on that another time.) But the best feature is it’s simplicity. First off, it has a built-in calibration tile inside the device for self calibration. (Device calibration is very important.) Also, as long as you have a monitor and video card that are DDC compliant, it can automatically take control of your monitors internal controls for brightness, contrast and color offsets and dial in the display to the proper white point and brightness as selected by you. On top of that, you can optionally choose to have it measure the ambient light level in your room and will take that into consideration when setting these levels. Once it gets the monitor level internally calibrated properly, it will proceed to profile the display and build the ICC profile as used by your computers OS to properly display the most accurate color possible.
Now we have an ICC profile and the display is color corrected. Great! Not necessarily. In fact, not all monitors are built equal. Some are designed specifically for high end graphic work and can display both a wider color gamut and have more accurate color rendering. These displays tend to cost twice to three times as much as a standard consumer grade display of the same size. Then again, even a consumer grade display can be calibrated for very good color. The thing that should be considered for those using non-professional displays is that the gamut is generally limited to the sRGB working space and even with calibration they may not render all ranges of color correctly. The worse case scenario are people doing color sensitive work on a laptop. Laptop displays often have smaller than sRGB working space and have very limited control over color and contrast. So even if you “calibrate” the screen and the tool builds you a profile and finishes with flying colors, it is not necessarily happily ever after when using the screen to make color sensitive corrections on graphics or photos.
The last part of calibration that can hinder color correction is our own eye. While many of us have less than ideal color vision, their is no way to correct for color blindness or poor color perception. Many people simply have lowered color sensitivity, even if they are not color blind at all. One way to test this is the Farnsworth Munsell 100 Hue Test which uses 4 sets of highly accurate color samples with very small hue increments between each step that you place into order based on what you see and check the results. (It sounds easy but it really is harder than it you would think.)
While having poor color perception does not prevent the monitor from being properly calibrated, it will hinder your ability to judge “correct” color on a calibrated display. Persons with lower color perception may want to leave final color corrections and judgments to trained professionals such as the techs at your professional level printing labs. People working at professional labs are generally selected for superior color perception (based on testing like above) and are highly trained to “see” even the slightest shift in color.
Here are a few other links of interest:
A site with several test patterns and other images. http://www.monitorsetup.com/
A good video by Will Crockett regarding monitors, lighting and print matching; presented by Moab Paper. http://www.moabpaper.com/shootsmarter1.aspx