1. As you can see this is a framed print. It's flat. It does what it's supposed to do - adds color to your set and decorates the walls of an interior set. You can do better!
2. This is the same print with a shadow effect. Notice how it seems to pop off the wall. This effect works best on a light background. The edges are kind of light when placed on a dark background.
3. This effect really pops the art. It has the appearance of depth. This is a good one to use in a moody room that is darker.
4. Another effect that works really well. This one is more subtle than number 3. This one would be used in a light filled room.
I showed these with artwork. That's what I use them for most often. However, they are perfect to use behind bookcases, china cabinets and anything else rectangle shaped that you want to pop out and add dimension to.
There are many more effects like these available on Polyvore. I find it best to save them as you find them then play with them to see what works best for you. As with these effects, the room will determine which one is appropriate.