The Monitor Color Temperature Question
Last week, we looked at the question of choosing the appropriate gamma value to use when calibrating your monitor. This week, it's time to consider color temperature.
Color temperature itself is an easy enough concept. Digital or film, you don't have to be a photographer for very long to encounter the fact that the color of your light source can affect the appearance of your images. As an outdoor photographer, I try to use this to my advantage by shooting most of my work during those "golden hours" early and late in the day. Throughout the day, the color of light ranges from around 3200 Kelvin at sunrise or sunset, to around 5500K at mid-day when the sun is overhead. When the sky is overcast or you are in the shade, the color becomes bluer, going to 9000K or above. Remember, while it seems backwards, low color temperatures look orange to us while higher ones appear blue.
The same is true of the light emitted by your computer monitor. The typical monitor has color temperature choices of 5000K, 6500K and 9300K. Some have more choices. Some won't let you change the color temperature at all. Natively, most monitors have a color temperature somewhere between 6500K and 9300K. If you use an LCD that offers a choice of "Native" white point, this may in fact be your best choice. If you use a CRT though, you will need to pick a color temperature.
If your monitor does offer a choice of color temperatures, chances are good that it came set at 9300K by default for the simple reason that the cool blue white color looks brighter than the warmer light from lower color temperatures. Just like when you go to a department store and look at the wall of color television sets they have for sale, your eye tends to be attracted to the one that looks brightest. But simply being brighter doesn't necessarily make it more accurate. Still, since your eyes tend to adapt to what they see without something truly neutral to compare against, most any mid-range color temperature will likely look reasonably good after a while.
So does any of this truly matter?
Setting the temperature too low will cause your monitor to work harder to achieve adequate brightness and may result in banding or other artifacts. Setting the temperature too high though will cause increased eye strain since the average indoor lighting from incandescent bulbs is down around 3400K. As a compromise, something in the middle tends to work best for most users.
Then there is the question of what effect this has on attempts to get your monitor to match your prints. Most of us don't have the luxury of controlling the color temperature of the light under which our work gets displayed, but the choice of lighting will have an impact on what it looks like. White paper will take on a warm or cool cast depending on the light source, and an image printed on it will too. If you are printing images to be hung under controlled lighting conditions, you can achieve the best match by setting your monitor to the same color temperature as the light source in the display area. If the light in your house is a mix of natural window light and artificial, you are again forced to compromise. If you sell your work, you are at the mercy of a light source you will likely never even see with your own eyes. Thankfully, everything else around your hung print will be under the same lighting and without any absolute frame of reference, the eye easily adapts, minimizing the problem to all but the most discerning viewer.
If you happen to have a higher end monitor, it may offer choices listed as D50 and D65 in addition to or in place of the 5000K and 6500K values. These are similar, but more accurate specifications published by the CIE or International Commission on Illuminants (Commission Internationale de l'Eclairage in French). The CIE took into account not just the color temperature though, but the actual frequency distribution of the light source.
So, if you use a CRT, you will likely find 6500K or D65 your best option. If you use an LCD, choose either one of these or the native white point setting. And there's no harm in experimenting with your monitor color temperature setting. Just be sure that if you change it that you re-profile it in order to accurately describe how it now reproduces color.