Help with images for sprites

[Playing Enemy]

What's up guys? I'm just curious if anyone knows how to pixelate a regular picture in photoshop so that it appears to at least been sprited a little bit, if not a lot. Thanks for any feedback. I'm making a screenpack, but some of the images look a little too clear to fit in with some of the other images.

[Spidermew]

If you have an image program that can work with layres, you put the image on the bottom layre and then on the layre above it you draw over it.

[Playing Enemy]

Spidermew, you are a genius. I use photoshop and I have no idea why I never thought to do that. I feel like an idiot now. Thanks for the help though, I'm gonna give it a try later and see what I come up with.