With the Hewlett-Packard PaintJet driver version 1.0, the "50% reduction" and "Precision bitmapping" options are only available with the following versions: (ones with "yes")
MacDraw 1.0v1 .............. no
MacDraw 1.0v4 .............. YES
MacDraw 1.1v1 .............. no
MacDraw 1.1v2 .............. no