print produces different results than export

Hi-

I'm recursively producing a series of PNG frames that I'll later use to make a movie. I set the size of the figure via

set(gcf,'Position',[200 1000 1024 768])

and them plot my data for a series of timesteps.

If I manually export the figure to a PNG file, I get the following.

This looks as I'd like it to look. However, it doesn't seem possible to us export to automatically output the image. Unfortunately, when I use

print('-dpng',frame_filename);

I get the following.

Clearly print is misinterpreting the Position and size of the figure. Has anyone solved a problem like this?

Raph