exporting just a single bar in a png file?

[Mark Freeman]

Hi everyone. I'm new to lilypond, so please bare with me.  I've
written a simple python script which takes a very particular
percussion notation and converts it to lilypond format. My script pops
this into a template and calls the lilypond command to create the
export.  Currently this produces a full pdf and I know I can turn on
png export with --png. I tried setting the template to clip only one
measure, but I still get a full page of output, even though the score
only consist of a single measure. I'm looking to produce a simple
image file that is only the single measure, with no extra score text,
etc... Is this possible?

Thanks for any help that you all can offer!
Mark