Flawless photo retouching. Smooth skin with frequency separation. Retouch with Dodge, Burn, Clone, Patch and Blemish Removal tools. Remove unwanted objects with the magical Inpainting Brush. Work in a dedicated liquify workspace to perfectly sculpt features. Colorize black and white photos, experiment...
APcanexport to 1-bit gif and png (using black and white preset) though it has no 1-bit work space. How to make a PDF of that is another question. And it should be noted that APalways dithersin export which complicates issue even more. Even if art is prepared to look 1-bit in ...
there was a program waaaaaay back in the MacOS 8 days that I've never seen replicated. (And the name of which I can't remember.) You'd import your 1-bit TIFF, then you could colorize it: either paint the black or else "color inside the lines" in solid colors. It would then be...