Color theory - "something red"

While writing that last post I found myself poking around on the web looking for some more information on color theory, of which I only knew the most basic points, and that mostly by intuition. I found an interesting explanation with examples to show how different background colors can have different effects on the impact a foreground color has, and can even make the color look like a different color. See the sections titled "Color context" and "Different readings of the same color" at Color Matters' Color Theory page. I can't reproduce the images here as they are copyrighted, but they're pretty cool.

I recently had some relatives from Italy visiting me. Her grandfather had been an early pioneer in photography. Her husband remembers when color photography first came on the scene and people were told to always have something red in their photos. They showed me their photos from their National Parks tour and indeed they chose on many of them to have something red in the scene. I'm not sure that bit of advice about something red isn't as outdated as "something old, something new, something borrowed, something blue," but Doug Plummer's photo of the day with the lady with the red shoes getting out of a car sure packs some punch, so maybe there's some truth to it. The photo accompanying this post, by the way, is the very first photo I ever took with my Canon 5D. Something red indeed!