[Therion] Embedding cross-sections based on bitmaps

[Michael Wasmund]

Hello,
I'm familiar with the method of embedding cross-sections made using scrap
editor. That works.
For our 10km - cave, we have 100's of cross-sections scanned from paper
(i.e., bitmaps), drawn decades ago.
How can I embed those? The method used for scanned paper surveys seems not
to work.
Whatever parameters I use, the cross-section scrap remains invisible. 
(Pls don't tell me we have to re-draw all the cross-sections)

Regards,
Michael.