A complete guide to creating striking black-&-white images in Photoshop. Work step-by-step through the four essential techniques for adding class by removing colour. Part 2 - Single Channels, Calculations and The Channel Mixer.
Photoshop offers an array of techniques for converting colour to B&W (or more correctly, greyscale), and these enable you to control the process with a degree of finesse that would be difficult to match in the field. In part one we looked at Desaturation. Here, we work through three other methods.
Method 2: Single channelsIn traditional B&W photography, colour filters are often used over the lens to create dramatic contrast, the reason being that hues that are quite different in real life can merge into one when seen in greyscale.
For instance, a strong blue sky with white clouds can appear weak in a B&W photograph. A red filter placed over the lens will darken the blue sky, making the white clouds stand out, because the red filter blocks the blue colour waves more effectively than it does colours that are nearer to red.
As a result, a red car in the same scene would look lighter. In short, when a colour filter is used in B&W photography it lightens elements of its own colour and darkens elements of its complementary (opposite) colour.