Lately I've been tinkering with a Steam app called "Pixage FX Studio", and it allows you to apply various filters to your photos, like pixelation, posterization, and changing color bit depth, among many other effects. It's on sale now for $4.49, though it does eat up about 6 GB of storage space, but in my opinion, it's worth every penny and megabyte if you're looking for an easy-to-use but powerful photo filter program. Highly recommended.

I do plan on working more with Pixage FX Studio as time goes on, and I hope to upload some examples of my own work in the very near future.