ICM tests and top-down DIB

Hi,

any suggestions about how could one reasonably test the ICM codecs?
I found no test at all in Wine (but the 4 Austin and I once wrote).

I was considering adding the ability to deal with a negative
biHeight values (native amstream seems to use this to work around bug
#17893) but I feel uncomfortable at touching the always
sensitive graphics area without good tests to start with.
Upside-down support in the codecs could start a landslide in other places.

Negative biHeight indicates top-down bitmaps, see
http://msdn.microsoft.com/en-us/library/dd183376.aspx

Grepping through dlls/* revealed only few places that deal with them.

Thanks for your help,
 Jörg Höhle.