I mentioned during the introduction to fluorescents that I would have follow-up posts about color temperature and CRI (color rendering index). I’m going to kick this off with color temperature and an explanation of why anyone would care about it.
One of the biggest problems with artificial lighting is that our eye and brain determine a lot of color information by comparison instead of some sort of mental color wheel. I’ve stuck an image file into this post to provide an example. The image to the right is made up of exactly 3 colors, but the purple color appears to be either a lighter or darker purple depending upon whether the adjacent color is the blue or the pinkish color. Also, the purple bar that runs all across the middle seems to change color from one side to the other.
The issue for artificial lighting is that as we look around us, our eye spots the brightest source of light and our brain “sets” that as white light. We are mentally doing the opposite of the what my sample image shows: instead of using relativity of colors to “see” either bright or darker versions of purple when the purple is actually the same, we are using relativity of colors to see different versions of “white” and then perceiving that as always the same “white.”
For the common user, a lightbulb (unless a specialty colored lamp) is going to be perceived as white. For the professional, we know that different sources are giving us different whites and we need a way to document the differences. We do that by specifying the “color temperature” of the source.
For the next post, I’ll explain what color temperature actually is and how we come up with the numbers.
Tags: color, color temperature, color theory, fluorescents, light bulbs
