It's always interesting to me to think about the light a painting may end up in or may be shown in. I work with north light or at night with full spectrum florescent lights, lighting my painting as I'm working on it. When it's shown in a gallery with hot and warm halogen or incandescent light the painting can look a bit (or a lot) different then when I'm painting it. I've been trying to make sure I look at my painting under stronger lighting at times as I'm working on it to see how it looks in this light.
Of course whoever ends up buying the painting will probably have different lights as well.... I'm also always curious to see how my paintings look on different computer monitors. I edit an image to look good on what I'm using but never know how it will look on others screens... Ah, the life of an image maker is an interesting one!