Regression from http://darcs.ghostscript.com/darcsweb.cgi/darcsweb.cgi?r=mupdf;a=commit;h=20100812141715-f546f-bd6036dbe947a55e9dbda923eb7c8a8b9e138e89.gz See http://code.google.com/p/sumatrapdf/issues/detail?id=1045 for a document failing to render correctly since.
This issue is due to the image mask being dropped during the conversion of indexed images. Obvious fix: http://code.google.com/p/sumatrapdf/source/detail?r=2176