PerlMagick is an object-oriented Perl interface to ImageMagick. Use this forum to discuss, make suggestions about, or report bugs concerning PerlMagick.
Add " type=>'bilevel', matte=>'false' " to the Write() method. See if that fixes the problem. In the mean-time we added a patch to ImageMagick 6.3.1-3 Beta so that the monochrome parameter automatically sets the image type to bilevel.