cosmonaut has a good point about adding contrast to a negative there is no going back, there was a scene i was shooting with my view camera it was sort of low in contrast, i increased my dev time a bit but it was a bit too much, the result of a very contrasty negative, i used a lower grade filter when i was printing it trying to get the contrast down, my result wasnt that great, the print looked dull and lifeless, wasted lots of paper trying to get it right I finally gave up, its a pain to try to burn in highlights.