I downloaded ImageMagick, and did this, but I can't figure out where it put the images, or even if it worked at all. Any advice would be wonderful.
Edit:
I figured it out. If anyone else is reading along and isn't sure what to do, open the command prompt in the folder that has the art and the line Phergus shared works without further fussing. If you do more than one sheet, move or rename your town images first, or the next set will overwrite the last.