VISIO, WMF, and PNG

[Joseph]

Several of the documents I work on use Visio drawings. I save the Visio
drawings as PNGs and then import the PNGs into FrameMaker. When I print the
frame book as a PDF, the PNG looks horribly pixellated.

On the other hand, when I save the Visio drawing as a WMF and use that WMF
in FrameMaker, there is almost no pixellation when I print to PDF.

I am not sure what the problem is here. I would much rather use PNGs, but
not if they are so pixellated they are almost impossible to view in a PDF.
Is it how Visio saves PNGs, or  my settings (e.g. screen res, settings in
viso for saving the graphic), or how FrameMaker is processing the PNG when
printing to PDF?

If there is anyone who successfully exports Visio drawings to PNG and then
imports them into FrameMaker, what settings do you use for your computer, in
Visio, and in Frame?

-- 
Sincerely,

Joseph Lorenzini