If you've ever used Fireworks to manipulate photos, you should know about the Auto Level filter. It's easy. It automatically corrects the lighting levels in a picture of choice. For normal photos, with people and stuff, it does well. The pictures usually become brighter and better without the colors drastically changing. For items, it's not always the same. Maybe cameras that add filters to certain types of content are partly to blame. When they make a forest seem greener than it really is, for example. I'm just theorizing though, I have no clue, I'm just going to throw in a couple of examples.
Here's a picture of when it works well.
Here's a picture of when it doesn't! I'm thinking of the lush green fantasy filter my camera has here. Could it be? Or not? Conclusions? Eh... none.