Try a Duotone
You can make a black-and-white photograph appear richer in tonal value by printing it as a duotone. In this technique, the shadow tones print with a dark ink (usually black), and a lighter ink (another color) is used to print the mid-range and light values. Depending on the second color you choose, the effect can range from subtle to harsh.
A variation of this is to use a gray ink instead of a color ink for the mid-range and light values, which retains the basic look of black-and-white photography but the overall tonal values are much richer than in an ordinary halftone.
For two-color projects, a duotone is a great technique that adds beauty and richness. Even in a full-color project, you get the impact value of the black-and-white photograph, but with a more elegant look. Keep in mind, though, that the second color is typically a spot color, so creating a real duotone in a four-color project often involves paying the extra price for that spot color.
Tritones and quadtones are similar to duotones, but obviously use three or four inks instead of two—this means two or three extra colors printed as spot colors. If the job is four-color process already, paying for two or three spot colors is usually prohibitively expensive for all except the most wealthy client (but when it can happen, it’s great).
(For specific details on exactly how to create duotones, tritones, and fake duotones, please see From Design into Print: Preparing Graphics and Text for Print.)
Another approach is to create a fake duotone: instead of making a halftone with two different values and printing the different values in different colors, create a solid color (or percentage of solid color) behind the image; the photo prints on top of the block of solid color, as shown below. This technique isn’t as subtle as a real duotone and the range of tones isn’t as rich, but it can give you another image style to work with.
To the right is a true duotone. Below, left, is a fake duotone using a background of a teal color in a value of 100 percent. Below, right, the background is 60 percent of the teal color.