'# build out an image directive like
# .. image:: somefile.png
#    :width 4in
# from an input like
# savefig somefile.png width=4in'

def process_image(self, decorator):

    savefig_dir = self.savefig_dir
    source_dir = self.source_dir
    saveargs = decorator.split('    ')
    filename = saveargs[1]
    outfile = os.path.relpath(os.path.join(savefig_dir, filename), source_dir)
    imagerows = [('..    image::    %s' % outfile)]
    for kwarg in saveargs[2:]:
        (arg, val) = kwarg.split('=')
        arg = arg.strip()
        val = val.strip()
        imagerows.append(('            :%s:    %s' % (arg, val)))
    image_file = os.path.basename(outfile)
    image_directive = '\n'.join(imagerows)
    return (image_file, image_directive)
