The various governments that have come up with the CDS are very secretive about it, but how it works has already been figured out. And, of course, unshackled software like GIMP happily ignore it.
Anyway, the BDP is making available on their website scans of the bills (face back), with the defacing word specimen printed over it.
But, if you take those PDF files, and run them thru pdfimages, it will give you decent rez (649 x 273) scans of the bills, without the defacing.