I'm trying to include a png figure and it works when I see it in dvi, but the ps comes in black and white.
If I compile directly to pdf there is no problem. However I'm using psTricks for a different figure, so I need to use ps first.
You have to convert your DVI file to PS using
dvips -I c <filename> instead of just
dvips <filename> (http://www.win.tue.nl/latex/faq.html#q16). The
-I switch is used to select image options, the
c stands for color, grayscale would be