TF2 Style Textures From Photos
After lots of messing around with photoshop I finally came across a technique for cartoonizing real life textures into a TF2 style. Hopefully this helps some of you who aren't very good at painting to create textures that fit the TF2 look.
Start with a texture that doesn't have loads of detail. The less detail, the better. I used this rock texture (which looks pretty fake already, likely from a zoo habitat or amusement park)
Apply Blur -> Smart Blur. Try the values I used, Radius 10 and Threshold of 30.
You should get something that looks like this. Most of the detail has been flattened out into solid colors.
Apply Stylize -> Diffuse. Make sure it is set to Anisotropic. This will give you a nice brush stroke effect.
When you are happy with the result, play with Levels or Brightness/Contrast to tweak the color value of the texture. Your end result should be something like this.