Display
If this question relates to the light falling on your display, the best answer is really “None” or “It Doesn’t Matter”. What’s important when calibrating your display is that the screen be the brightest light source in your viewing environment – you don’t want it “competing” with the ambient light. Thus, the most fanatical color professionals work in a darkened room with a relatively low brightness display. Under these conditions, the color temperature of the ambient light doesn’t matter much, because it is not really in the mix.
However, many people don’t prefer to work in a cave and therefore have natural or electric light in their work environment. Again, it’s important that the display just be the brightest light source. So if you have a fair amount of light in your environment, TruHu encourages you to turn up the brightness to compensate for that. Thankfully, most modern LCD displays can get pretty bright and compensate for most viewing environments. However, if you have your display set to 100% brightness to compensate for your viewing environment, be aware that you are likely dramatically shortening the functional life of your display, maybe by 50%.
Viewing Print
If you are viewing prints and trying to match to a screen, then the type of light that you are viewing your prints under is very important. For most people, if you have access to a window in your work environment, that will be sufficient. Outdoor lighting has a color temperature of 6500K (see 6500K vs 5000K blog post). Depending upon your paper, you should be able to find a White Point in TruHu that will serve as a good match.
If you want to be a bit more buttoned down, you can purchase lamps with a known color temperature – 5000K is the norm for print viewing in the U.S. But not all 5000K bulbs are created equal. On Amazon.com, a case of 25 48” fluorescent bulbs rated for 5000K can be found for $86 ($3.44 per bulb, as of the time of writing). Meanwhile, a single 48” 5000K bulb designed to be used in a graphic arts viewing booth will sell for about $50. What’s the difference? – take a look at my Quality of White Light blog post.
