How to convert a color photograph to black and white using Photoshop

The Puddle On Sandstone Walls, Coyote Buttes, Arizona, USA

How to convert a color photograph to black & white with Photoshop Channel Mixer

The perception of reality is in color. Rendering that color to a black and white photograph, in addition to being a personal option, it is also an art.

In chemical photography, on first instance the one interpreting the color is / was the film, mainly panchromatic, which has / had the “defect” of rendering greens as darker and the blues as lighter than human appreciation. We can / could modify these renderings to some extent, with the use of filters at the time of exposure.

With digital technology, we can now alter black and white color rendering in a number of ways, among which I personally prefer Photoshop’s RGB Channel Mixer.

The following images are not intended to be a tutorial of the process but a starting point and inspiration for each one to find their own way.

It should be said that this process is almost never used in the entire image, but locally on parts of the image where we want to modify such rendering.

Original 4″ x 5″ inches color slide.

Conversion to Black and White with adjustment layer.

Final result using Channel Mixer. Note the crystal clear water as the blue reflection has been lightened.

(Click to enlarge)

This image shows the “normal” process of converting to black and white using layer adjustment. The result is similar as converting an RGB file to Grayscale.

The sliders are very similar to those found in other applications such as Lightroom. These settings can theoretically do the same as using Channel Mixer, but as they also have complementary colors such as Yellow / Cyan / Magenta, it is easy to get out of hand and get unwanted effects, such as posterized areas or unpleasant white edges (from lens chromatic aberration).