For a long time I've been working with photos, either using the photo itself or duplicating it someway in fabric. For years, I would go to a home improvement store, bringing the photo with me in hopes of matching colors with paint chips. It worked pretty well, but time consuming and often some colors were overlooked. The photo below has lots of greens in it and what looks like a gray and rust.
Color Palette Generator and start uploading your photos, you'll be hooked. You can see the sample below (which they allow you to print out) of colors and the picture that was uploaded.