Why Desaturate Isn't Always the Best Way

As you can probably tell, I love doing things with colour. However, there is also a time when a lack of colour can be even more dramatic than an abundance of it. Usually, to remove colour from a picture, we use the desaturate tool (which can be found under Image -> Adjustments -> Desaturate in Photoshop). However, with proof from this tutorial and the added pictures for examples, you can see that desaturate is definitely NOT the best option to make your photos black and white! There's another way that can give you a much more dramatic black and white.

Take this picture of a flower



When you desaturate it from the Photoshop desaturate, it essentially removes all of the colour and gives a value of grey that is based on the colour percentages. It gives us a fairly decent black and white photograph, but it could be much better. Here's what it looks like desaturated



See? It's a fairly decent black and white. However, if we manipulate how the colours are taken away and what levels of black each colour has, we can change the way the image looks in black and white. We do this using the Channel Mixer. By tweaking the levels in the channel mixer, the reds can become darker, or the blues, or the greens, which gives a different look to the image when it becomes black and white.

Now we can drag the RGB sliders to change the proportions of what goes in to the final grey image. To gain a similar result to Desaturate, just pick 33% in each channel. Note that the dialog box shows you the total output. When mixing, try keeping the total output 100%, although this can be ignored if you really want.

Here are images created with 100% of Red, Green and Blue respectively with the other colours 0%:

If you tweak the levels, adding different varieties of tweaks into different layers and then blending them using multiply or overlay, you can create a really nice black and white effect that is much better than what a simple desaturate could do. Here is an example of a tweaked black and white photo versus a plain desaturate.

In conclusion, desaturate is a great tool for when you want to make something black and white very quickly, but if you're going for something dramatic, it takes a bit more effort. I suppose the same can be said for many things in life. But at least now you know how to do this one!

Happy Desaturating.