Barcodes in SVG

I am currently using Batik as part of a workflow to print badges for a
convention.   I have a java desktop application which:

   1. polls a web server for badges to print
   2. retrieves the data (type, template name, person's name, id, etc...)
   3. loads an appropriate SVG template
   4. Uses ZXing to generate a code-128 barcode and an QR code
   5. Loads the appropriate picture for the badge
   6. converts the barcode and picture PNGs into data: urls
   7. find the appropriate elements in the svg dom and replaces the dummy
   images with the picture and barcode data: urls
   8. sets the batik transcoder output resolution
   9. rasterizes the svg to a png file
   10. sends the png to a photo printer

The problem I am having is that resulting badge png has artifacts in the
barcodes.  They're either antialiasing or scaling artifacts.  This makes
the barcode a little hard to scan with readers and slowed down our
registration system.  Does anyone have any suggestions on how I can keep
the barcode images as crisp black and white images inside the full color
badge?

Thanks,
Robert