Yes but you said Mono 8 wasn't working correctly, that it was producing images iRex didn't like so you'd stuck with RGB.
To do what needs be done Poppler needs a byte packed Mono 4 mode. My explorations revealed that Poppler would also benefit from an internal Mono mode. Right now all the Postscript primitives render RGB and get converted to Mono 8. In several key primitives, such as DCTStream handling, there are significant performance boosts to be had by going directly to Mono (no chromatic decode from DCT, a significant savings...)
Anyway, thank you for your prompt processing of my Shell Access Request. It feels good to be back on the mainstream again.