Please write image files in a vector graphics format, when possible, and generate the .png and .pdf versions on the fly (see ../Makefile). Recommended tools are dia, tgif, and xfig. Store the .dia, .obj, or .fig versions in mercurial, but not the .png or .pdfs. Note: tgif can convert from .obj to .pdf, but the pdf that results takes up a whole page. Instead, we convert to an intermediate .eps step, and then run epstopdf.