Combine JBIG2 files into PDF

Hi,

I tried asking this on the magick-users list, but no-one replied. So I
thought maybe it fitted the category "Usage questions which are too
arcane for the normal user list should also be posted here" and would be
suitable for this list... ;-)

I have a set of scanned JBIG2 files that I would like to convert into a PDF.

At the moment, I use

"convert -units PixelsPerInch -density 600 rawname.jbig -rotate -90
output.pdf"

However, the PDF files that emerge from this seem to be much larger than
the original JBIG2 images.

I know that PDF files can contain JBIG2 images. Is it possible to have
the raw JBIG2 files wrapped into a PDF by ImageMagick without internal
conversion to another bitmap format?

Many thanks,

Chris.