There's many different techniques to separating 'black and white' photo real images. the most common method is simulated process, using halftones. with that method you can do as few as two screens (black ink and white ink). depending on the ground color you could add an underbase for another level of detail. The ideal method is using multiple screens including at least 1 grey, 2 is preferred. I personally prefer 5 screens (underbase, dk.gray, md.gray, black and highlight white) giving the print allot of depth and detail. i find using just black and white the print looks flat as there is too much contrast between black and white ink to mix on press smoothly.
another method i use is index, altho this isn't as ideal as halftones for smooth gradients it does do a nice job if printed accurately.
another method i use is index, altho this isn't as ideal as halftones for smooth gradients it does do a nice job if printed accurately.
