Okay, after much tweaking and cursing I managed to get the colors back to where I want them. It was a lighting issue totally unrelated to the filters. Magical "use material curves" button, oh how I love thee! And I think I've got the falloff to look pretty good for the fog effect (new settings posted). I still need to go and fix the texture on that sign, it looks like its been through a sandstorm. Let me know what you think!