In my black and white photography class, we're learning how to develop and print our own film. I took the class because it's a prerequisite for most of the other classes at the school. Much to my surprise I'm loving it, notwithstanding the need to stand in a darkened room with noxious chemicals for hours on end. Go figure.
Anyway, last week's lesson was about contrast. The more contrast, the more middle gray tones move to either white or black. The following pictures were printed (enlarged or whatever the heck they call it) with different contrast filters. These are physical filters made of colored plastic gel that magically affect the contrast of the photo being printed/enlarged.
The topmost photo shows the effect of a #1 contrast filter, which reduces the contrast. The second photo was created using a #2 filter, producing normal contrast. On the last three photos I used #s 3, 4, and 5 respectively, which as you can see, increase the contrast. The result of using five different contrast filters is five different "takes" on the same picture. Pick the one you like the best. You can do the same thing for digital photos in a photo editing program.