(My apologies if this isn't in quite the right place. I"m new to Cartographer's Guild.)

I have a scanned image (.pdf) of a commercially published fantasy map which shows the better part of a continent. I would like to measure travel distances between points on the map. Straight lines are easy, but roads and rivers aren't straight.

I can't find a way to measure non-straight lines in Photo Shop CS3. (Doesn't mean it can't be done just means that I can't figure out how. )

I found a plug-in for GIMP that "measures active path" but the download is in Python. I went so far as to install Python and use a utility to turn the .py into an .exe, but no dice. GIMP does not like it.

I've become so obsessed with finding a solution that I've considered using GIS software and creating a false data set for the map. (This should be a clue as to my current mental state.)

I hope that my mind is merely clouded by my obsessive state and a simple solution exists. Please, please help!