For an overview of what you can do with GD I would suggest installing GD::Graph and then running its example scripts and examining the output.

I have no idea whether you can get acceptable resolution with it, or if its features are sufficient to your needs, but that should be enough for you to evaluate it.

Also I suggest adding Image::Magick to the list of alternatives that you are examining. It uses a different underlying graphics library with different capabilities. (Another candidate is the Gimp, but not having had occasion to use either I can't seak to their capabilities.)