I wrote a tool that turns Warcraft 2 PUD (map) files into really big BMP images. There's also a batch script that runs the produced BMP through a PNG converter to losslessly compress the file, and another one that recursively plows through a directory doing PNG conversion on every PUD found.
Requires some files extracted from the Warcraft 2: Battle.net Edition datafiles in order to function.
It's all released under the GPL. You can get the program or download a couple big ZIPs of pre-rendered images for all the official maps and all the KPUDs.
Check it out: http://nwserver.webhop.org/pud2bmp/
In the future I will roll this up into a much larger tool for as many real-time strategy map formats as I can discover... C&C, Red Alert, Warcraft I and Starcraft are next on my list. It will be called Stratlas.