Ok, this is an early version. It is targeted to UOL, but may be useful for others.
It doesn't do dif files by the way.
The package includes the dll's , as well as two xml files the program needs. The xml files need to be in the same directory as the application.
The Altitude.xml file is exactly the same as the UOL one. So if you have changed it, then copy that one into the mul2bmp directory.
The Terrain.xml is the same as the UOL one, with an exception. Under the entries, add the tile entries that should map to the tiles that should equate to the color you want.
At the moment, I don't parse the static files (perhaps later), but this should work fairly well.
So again, if you have modified the Terrain.xml file, you need to merge (not copy) that information with the Added entries mul2bmp requires (fyi, you can use the same xml for both programs. XML has one ignore the tags it doesn't understand.) So once merged, you can use it for both programs.)
UOL doesn't use all the terrain ids, but if you are going to use it other maps, you may need all of them. By default, if a tileid isn't maped in the xml file, the program will map that to the index 0. But at the end of the generation, it will create a file "notfound.txt" that will have all ids that were in the mul file that it couldn't find. So you have a hint of what ids you need to add.
As for the terrain.xml file. I did a start, but it is far from complete (and it may not be totally accurate). Hopefully those who use it wil give some updated terrain.xml for later incorperation.
The link where the package can be found is:
http://members.cox.net/ckerr59/mul2bmp.rar
To create an image , just do a file->open and specify the map mul file you want. It wil generate both. When doing a file->save (to save the images), one specifies the directory where the altitude.bmp and terrain.bmp files will be saved.