How can I save the view(biograph) figure at a high resolution?

When I use the view(biograph) to get a picture of my mass biograph object(329 nodes), it's too small to get a clear view, but when I use the enlarge tool on the tool bar, it becomes more satisfying, but when I tried to export it, the output image only contains the part of the figure showing on the screen. How can I get a high resolution, say over 5000X10000, and complete universal image format(png)?