Last modified: 2013-04-24 09:18:40 UTC
transparent images makes it easier to include the image inside a infobox with a background. See bug 8 (math extension) or bug 31736 (WikiHiero extensions) for similary requests.
Seems like this might require a separate call out to convert. You can change object colour fairly easily (in the code on the page no less), but background doesn't seem to be manipulate-able in the same way https://lists.gnu.org/archive/html/lilypond-user/2008-08/msg00995.html
Extension uses ImageMagick so possibly could transform white background to transparent.