Back in the days of film, creating a black and white image was a relatively simple process. You bought black and white film, developed it, and printed it on black and white paper. In the digital age, it is also simple to convert color images to black and white. However, as with all things digital, there are numerous ways to do this, from a simple desaturation in Photoshop to using powerful, Photoshop or Lightroom plugins such as Nik or Topaz Labs. There is one method, however, that is both fairly simple and highly customizable; using Photoshop’s Channel Mixer.
As with all black-and-white conversions, the most important aspect for the conversion is choosing the right image. Obviously, the very best images will be ones that have been specifically shot with black and white in mind. If you want to convert a shot that wasn’t conceived to be black and white, try to choose an image with reasonable shadow detail and contrast, such as a landscape with some definition in the sky, or perhaps a nice contrasty portrait.
With an image selected, let’s get to work.
Open your image in Photoshop. (For this tutorial we are using Photoshop CS6.) In order to see what you are doing, you need to look at the Channels Palette. This can be found in the Palettes window to the right of the screen. The default palette is usually Layers, but at the top of this there will be a tab for Channels. Click on this to see the RGB channel and the three individual color channels. By clicking on each of the individual colors you can see a preview of how significant each primary color is in the image when in black and white – useful for when we actually carry out the conversion.
The Channels Palette
In order to preserve the integrity of the original image, we are going to use the Adjustment Layers tool. From the Photoshop menu, select Layer – New Adjustment Layer – Channel Mixer.
A pop-up window will open, allowing you to name your adjustment layer. Give it a suitable name and click OK. You should now see the adjustment layer appear in the Channels palette as well as a new Channel Mixer palette. On the Channel Mixer Palette, check the monochrome box.
Create a new adjustment layer
At the top of the palette, you will see a Presets dropdown box. This has a number of presets including Infrared, and typical black and white filters such as the red filter or the blue filter. You can either use this as a starting point or, if you would prefer more control, you can use the main RGB sliders.
The channel mixer has a range of presets
Because the color information is still in the image, moving these sliders will affect only the color in that channel. For example, if you move the blue slider to the left, this will filter out the blue light in the image, making blue skies go darker. If you slide to the right, you are effectively filtering out yellow, the secondary color to blue with the effect that the blue sky will become lighter. For the red channel, the secondary color is cyan, and for the green channel the secondary color is magenta. By using a combination of one, two or all three of these sliders you can process the image exactly the way you require and mimic traditional, on-camera, black and white filters.
Here I have used the red and blue sliders to darken the sky and lighten the building
At the bottom of the palette, the Constant slider acts as a type of gamma control, allowing you to lighten or darken the overall image.
Once you are happy with the final result, it is time to save the image. If you wish to preserve the layers for adjustment at a later time, then do not merge or flatten the image. From the Photoshop menu, go to File – Save As. From the save dialogue, select a suitable file name and location and then choose either Photoshop PSD or TIFF file in order to preserve the file’s layers. If you also want to have an easy-to-use JPG, go to the Photoshop menu, Layer – Flatten Image and then save as before but selecting the JPG file option from the dropdown box.
Black and white images can be incredibly powerful even in today’s colorful digital world. Using Photoshop’s channel mixer is an excellent way of maintaining control over the look of the black and white image, allowing you to recreate the looks of on-camera black and white filters or your favorite style of black and white printing such as a high contrast grade 5 paper look.