Hi CCZ,
dpi usually refers to a printed image, so the printer settings control the resolution. For example, draft versus normal versus high quality. The software can create images up to 9999 by 9999 pixels. At 300 dpi, that would give an image 33 inches square. What size printout do you want? (in inches or cm)
I vaguely recall something odd about the legend. It's almost as if the software assumes some dpi, and the selected size of the image in pixels would determine the physical dimension when printed. The legend is scaled so that when printed at that size, the text is the "correct" point size. So if your printout is not the unknown intended size, the legend will either be larger or smaller than desired.
Let's assume the software intends 100 dpi (I have no idea what the real value is), a 12 point font in the legend, and an image size of 1000 x 1000 pixels. If printed at the intended size, it would be a 10 inch x 10 inch image, and the legend would be a 12 point font. If you print the image as 6.5 inches wide, the legend size will be equivalent to 12 * 6.5/10 = 7.8. So when an image of thousands by thousands of pixels is printed on a normal size piece of paper, the legend becomes very small.
The work around is to set the legend font to a much larger number. Even though it will appear to cover a large area of the screen, is will be "normal" size when printed.
I normally save images in PNG format.
