Photoshop Tip: Converting Color Images to B&W

PHOTOSHOP TIP: Converting Color Images to B&W
by Michael Frye

How do you turn color photographs into B&W? While there must be a dozen ways to do this in Photoshop, my favorite is to use the Channel Mixer, because this gives you the most control. Here's how to do it:

First, start with a color RGB image. To make it easy to undo your conversion at any time in the future, I recommend using an adjustment layer. Go to Layer > New Adjustment Layer > Channel Mixer. You'll see a dialog box that looks like this:

Check the Monochrome box in the lower-left corner. Your color image instantly becomes black and white--but you're not done yet! Photoshop defaults to using 100 percent of the Red channel, and 0 percent of the Green and Blue channels, and these percentages may not be the best for your image. The beauty of the Channel Mixer is that you can combine these percentages in any way you like to make the best black and white image.

100% red is similar to using a red filter with B&W film. 100% green is similar to using a green filter. And, you guessed it, 100% blue is similar to using a blue filter. But you're not limited to using only one channel. You can use 30% red, 50% green, and 20% blue -- whatever works best. Just make sure the three percentages add up to 100%--or close to it.

To make the B&W image at the beginning of this tip, I started with this color image of Sentinel Dome and added a Channel Mixer adjustment layer. Using 100% of the red channel made the image dramatic, but a little too dramatic. So I backed the red off to 70% and added 20% green and 10% blue:

That's all there is to it! The Channel Mixer is simple but powerful.