simg:getWidth and relative pathnames

Hi,


i want to use simg:getWidth to find out the intrinsic width of images (used as terms in a variablelist). but it seems like simg:getWidth only works with absolute pathnames.
i use relative pathnames with my images (they are stored in a subfolder of the folder containing the .xml)

is there a way to find out the folder the .xml is contained in?

thx in advance,
	Sebastian Fey