Photoshop offers up a huge variety of ways to create stunning black and white images -- and I don't just mean choosing Image > Mode > Grayscale. For photographers, or even for those who want their images and photos to look their best, there are a variety of choices for creating rich black and white photos in Photoshop, and many of them are non-destructive; meaning your original, full color image will remain intact and unharmed.
However in this tutorial, we'll look at a technique for creating a rich black and white effect that is destructive, or permanent, so you may want to back up your photo before we begin.
Go ahead and open up the photo that you'd like to apply the black and white effect to. The photo that I'm using is of one of our local miscreants, and as you can see, the photo is a bit washed out in terms of it's color and contrast. No worries, that shouldn't matter too much for our effect.
For our effect, we'll be using Photoshop's Channel Mixer. Go ahead and open it up by choosing Image > Adjustments > Channel Mixer. At the bottom of the dialog box, turn on Monochrome, and voila, you have yourself a black and white photo!
Now, we could leave things as they are, but one of the reasons I like using the Channel Mixer when I'm creating black and white photo effects is that we have the ability to fiddle and play with our darks and lights. So in the Channel Mixer dialog box, try experimenting with the Red, Green, and Blue sliders until you achieve a decent result -- a rich, stunning black and white photo.
As you can see, you can really fine tune things. And using the Channel Mixer offers a heck of a lot more control than simply changing the image's color mode to grayscale or desaturating your image (Image > Adjustments > Desaturate). Try moving the sliders in small increments, and don't forget about the Constant slider at the bottom.
Find out more how-to's on Photo Retouching in Photoshop.