You could check out the source for the GPD which is what I use in Eclipse to define my jPDL and it automatically creates a png copy of it.
It does rely on the x,y,w,h co-ordinates though which probably will be the hardest bit.
Unless the processes are simple a->b->c->d then I would investigate employing a diagram layout algorithm. Check Google for some answers.
You could also use alternate tools to generate a BMPN diagram and then import it but I don't know if that would fit with your project.
thank you for your valuable contribute. I've checked the source code which can be used to generate at runtime the process graph.
It's a great piece of information- unfortunately I'm missing the X,Y coordinates since the process graph is generated at runtime.
I think there should be some libraries which can calculate the process coordinates based on an abstract set of nodes and transitions;
Should I find anything, I'll post on this thread some news.