Ronald Vermeij

Blender - Cycles - How can one create a normal map?

As follow-up on my question about transparant plastic foil pattern I was wondering:

How can one create a normal map:
- Can this be done inside Blender?
- Can this be done by manipulating a(ny) texture into a normal map?
- Does one need external programs to do so?

Thanks for all hints, tips and tricks.