Beads, especially seed beads, are all about color and how one color interacts with other colors. Somewhere in my travels through the web I came across a site that takes your photos and generates a color palette. Not a new idea, but this one is free to use and it gives you an idea of different colors present in a photo that is very useful when trying to create more realistic color effects.
The Color Palette Generator from Big Huge Labs is available on their website.
This is a screen shot of a photo and the color palette that was generated using it.
The color noise can be eliminated by using a close up image like this flower.
There are lots of other fun tools on the website. One will take your photo and put a circle grid over it so you get a sort of beaded effect. It's good for a quick look, but the resulting image is kind of grayed out. It does give a general idea though and it's easy enough to do.