Shop Talk: Create Better Black-and-Whites from Colored Photos

Converting your digital colored images to black-and-white photos is easy, right? All you have to do is Desaturate your image or change its Color Mode from RGB to Grayscale. However, if you want to create more striking black-and-white photos, first try out the following methods instead.

1. Use the Channel Mixer
   Go to Image>Adjustments>Channel Mixer in Photoshop, or to Filters>Colors>Channel Mixer in GIMP, then turn on the Monochrome option. Input a value of 100 for the Red channel, and a value of 0 for the Green and Blue channels. Then, do the same for the Green channel, then the Blue. Doing so allows you to select which of the three channels best highlights your subject. Once you've chosen one channel, you can adjust the values of all channels to improve the contrast of your image. To keep the brightness of the image at the same level, add the values of the Red, Green and Blue channels, and keep the total of the values close to 100.


2. Use the Lightness Channel
   In Photoshop, convert your image to LAB mode (Image>Mode>LAB), then pick the Channels palette, and delete the A and B channels. This leaves only the Lightness channel. Convert the image mode to Grayscale.

   To do the same in GIMP, you simply go to Image>Mode>Decompose. Choose LAB option, with the Decompose to Layers option on. This will produce a Grayscale duplicate image with three layers containing the different channels. Delete the A and B layers.

   All you have to do next is adjust your photos contrast using Levels or Curves.

In GIMP 2.4.x, Channel Mixer and Decompose can both be found in Colors>Components.