[Award Winner ] Creating an old-school map in Gimp.

[Ghalev]

With a photocopier, it has to be blue, because of the blue glass plate within the machine itself (which is also what causes red to go "black"). But with a scanner things are a lot more flexible ... A lot of [the hand-drawn elements in] my maps were actually drawn in magenta, orange, blue, green or other colors using markers, for example, precisely for that reason ... it's a snap for Photoshop to suck away or isolate the color.

[RPMiller]

If you use Cyan for pencils and for PS it is extremely easy to knock out your sketch marks since you can just dump that channel and convert to RGB, or so the experts tell me.