Ever
see those images that have most of the image as B&W with one or
key elements in color? Or an image with almost unbelievable colors?
There
was a technique back in film days, where we printed B&W and
then hand colored certain elements. Now, we can do this digitally.
Some
image manipulation programs programs allow you to paint in a color on a
layer or an outlined area. Other programs allow you to desaturate all
the colors except for what you want to be color. Check your programs
help section or a tutorial to find out how to do this in your own
program, several are very different from each other.
Even
with the neat effect, the subject matter still has to fit the
technique. Maybe lips and eyes for a portrait, rays of sunshine in a
landscape, or a flower popping out from the background. Or even an old
car in a cityscape. Get creative!
Using
many of the same controls, we can enhance, or even change, colors
selectively with a color image. Trees not yellow or red enough? Change
it. Need a bluer sky, or even a different color sky? Change that, too.
How much depends on your vision for that image. You can keep it fairly realistic, or "interpret" it as you see fit.