Thanks for the reply.
I did try a program that would convert raster to vector some time ago and the results were pretty messy indeed. Not to deter anyone from trying though I have to admit I didn't devote too much time learning that program.
Since I don't know a thing about photo programs I was only guessing that there should be some kind of a tool or command that will allow you to define a certain tolerance and delete all the pixels below that setting, thus (still guessing here) removing unwanted noise and maybe reducing the thickness of the lines. That's what I had in mind initially.
Anyway enough with derailing this thread.