I stumbled across this the other day while using excel to make my printable maps for Gencon. It's a simple technique and gives your dungeon maps an extra spark with very little effort.
|Start with a map like the one below, a classic black and white map you could do up in excel.|
|Next, insert your image into excel (insert, picture) and in the format tab, choose "Set Transparent Color". Choose a black area in the picture to make your black part of your map transparent.|
Your map should look like this, now that you've selected the black portions to be transparent.
|Finally, right-click on the picture and choose "Format Picture". Choose "Fill", check "Picture or texture Fill", and click on the button "Insert From: File". Choose a texture file that you have (and if you don't have one, just search for any cool dungeon wall texture files on the web... they're easy to find).|
|Doing these steps will yield the picture below. Now, since the statues and pillars were black, they too got replaced with the texture. If that is not desired, you could instead pull your original texture into Gimp (or similar program), replace the outside black with bright green, and then make the bright green your transparent color.|