Get original image format and msoPicture Export command   

1.
Is there a way to get the original format of an image?
I export a msoPicture shape using its Export command. Usual "jpg" gives 
me the best file size, but for semi transparent images I would like to 
use gif. Probably the easiest way would be to just get the original 
format and use that or something like:

if (origFormat == "gif")
   useGif
else if (origFormat == "png")
   usePng
else
   useJpg

2.
Is there some documentation about a shape's "Export" method? I just have 
found an example and some hints but no real documentation.

Thanks
Daniel

date: Wed, 30 Jul 2008 11:54:12 +0200   author:   Daniel Kirsch