Although easy colour photography has been around since at least the 1940s, monochrome or “black and white” photography remains popular to this day. There’s something about black and white that really works for some subjects, bringing out texture, form and detail that the more realistic depiction of colour somehow misses.
With the right choice of subject, a good well-exposed monochrome image can become a work of art. Almost all digital cameras include a black and white mode, and as you’d probably expect Photoshop offers multiple methods for converting colour images into stylish black and white. For this section we’ll use this landscape photograph. It’s got some strong shapes and colours, and the excellent textures will also prove useful for the conversions.
The quickest and easiest way to turn a colour picture into a monochrome one is to simply remove the colour. It’s called Desaturation, but it’s very crude and offers no creative control at all. The resulting image is not too bad, but it does look a little flat and lifeless, with reduced contrast, tonal variation and highlights are not as strong. Some of the texture needs to be able to stand out a little better. Nonetheless, if all you want is a quick-and-dirty monochrome conversion, you’ll find Desaturate in the Image > Adjustments menu and it will suffice for most of your mono conversion needs if you’re not going to work on it further.
Another method for removing the colour from an image is to convert it from a normal RGB (Red Green Blue) colour image into a monochrome greyscale image. This simply discards the colour information from each pixel, leaving only the brightness information. It will preserve the full range of tones from the original picture, but like Desaturate it offers no creative control. The results do look slightly better, with greater tonal range, but it still looks a bit flat, and furthermore greyscale limits some further editing options. You’ll find Greyscale in the Image menu under Mode.
Most colour pictures that you’ll come across are made up of a mixture of three primary colour channels, one each for red, green and blue. With these three primaries it’s possible to make any other non-primary colour. Most modern forms of colour imaging use this method. Digital cameras have an RGB colour filter mask in front of the sensor to provide colour information, TVs and monitors display colour images as an array of tiny red, green and blue dots, and even your eye detects red, green and blue pigments, which is why some people can have colour blindness in one or more of these colours. Photoshop also uses colour channels, and you can see how this works by activating the Channels palette.
You can see what each channel looks like independently by clicking on it, which will turn off the other two. Compare the three channels, noting how the relative brightness of different areas such as the blue of the sky or the reds and browns of the rocks change from one channel to the next. You can select and save just one channel by activating it and using the Greyscale mode option to discard the other channels. This does offer a bit of creative control, but it’s a bit crude.
The Channel Mixer
One of the best ways to convert a colour image to monochrome is to use the Channel Mixer. This takes the RGB colour channels that we just discussed, and offers a way of mixing their output into a black and white image. You’ll find the Channel Mixer in Image > Adjustments > Channel Mixer.
Until the introduction of the Black and White menu and adjustment layer option in Photoshop CS3, the Channel Mixer was the preferred method of converting to monochrome for many photographers. Open the channel mixer and check the box for Monochrome at the bottom of the panel. The image will immediately convert to monochrome, but now you can adjust the channel sliders to alter the relative brightness of the tones in the image.
Black and White
Until Photoshop CS3 came along in 2008 you would find dozens of online tutorials offering home-brewed methods for converting colour images to monochrome. The Channel Mixer offered one approach, giving some control over the relative levels of tone, but the Black and White function takes that control and offers even more. It’s available as an Adjustment Layer, so it can be used non-destructively, keeping your base image untouched.
Black and White offers complete control over the tonal balance of your image, with channel sliders for the primary red, green and blue, as well as non-primary yellow, cyan and magenta, so you can fine-tune tone and contrast, emphasising any other colour range. Each slider adjusts the relative brightness of a particular channel.
The Black and White function also provides an easy and effective method of applying tints to monochrome images, accurately replicating old but popular processing techniques such as sepia or cyanotype toning, both of which can add a lot of atmosphere to the right sort of picture.
Starting with the same settings as before, with the Black and White sliders set to enhance the image check in the Tint box. The default setting is something that looks a lot like sepia, but in fact it’s not quite right, according to most popular opinion. If you’re using the Black and White function from the menu option you’ll see Hue and Saturation sliders at the bottom of the control window.
For a nice approximation of the blue tone typical of cyanotype toning, set the hue slider to about 220-230, and move the saturation slider to the left so that the blue tint is quite pale. If you’re using the Black and White adjustment layer technique (a much better method), check the tint box and then click in the small coloured square next to it. This will bring up a Photoshop colour picker window, offering a much better way of controlling the colour and intensity of the tint. For a recreation of sepia toning, set the hue to about 40 for an antique feel to the image.
This guide, and many more like it, can be found in The Adobe Photoshop Manual Vol.14