The PXL unimplemented compression mode 2 (jpeg) has crossed my mind from time to time, especially when some complains about output sizes. Most of the output size issues can be addressed by deltarow, the rest needs some higher-level conversion of rectangles to images (there is a patch sitting on my hard disk to do that, but it needs a bit more work...). Given the lossy nature of jpeg compression, one might not want to take this option if there are other alternatives. So just file this so this option isn't forgotten, and see if anybody has a good incentive/reason to request this.
pxl compression mode 2 (jpeg) posted as part of bug 691880. http://bugs.ghostscript.com/attachment.cgi?id=10746&action=diff In anticipation, change from LATER to FIXED. actual commit info will be posted in bug 691880 .