Converting Color Photos to Black & White

Favella Rocina, Brazil: Beth Cook
Digital Color Photograph Converted to Black & White

 

A quick glance through any photography or fashion magazine, or at the photos on social websites like Flickr, confirms that black and white photography is as popular as ever. With the coming of digital though, one important thing has changed. In the days of film photography, you shot on black and white film. Now, with digital cameras, you take photos in colour and then convert them to black and white.

 

La Romana, Dominican Republic: Beth Cook
Black & White Film Photograph

 

In this article I will run through the most commonly used black and white conversion methods, outlining the pros and cons of each. (Instructions are provided for Photoshop CS5)

 

Converting to black and white digitally has a number of advantages. With film, the black and white conversion essentially happened at the time of shooting. If you wanted to change the nature of the black and white conversion, you could only do it by placing a colored filter on the lens (a red filter, for instance, makes blue skies much darker).

Now, by starting with a color photo and converting it to black and white in Photoshop, you have complete control over the conversion. Darkening a blue sky is easy, once you know how, and you can decide exactly how dark you want it to be.

1. Black and White Conversions

Photoshop and Photoshop Elements offer both destructive and non-destructive black and white conversion techniques. Destructive methods are ones that can’t be re-adjusted afterwards. Once you’ve made the conversion, the only way to change it is to undo the conversion and start again.

Non-destructive methods use Photoshop’s adjustment layers. The changes that you make to your photo are stored in a layer, and the original photo remains unchanged underneath. Then, when you’re done, you flatten the image and it’s as this stage that Photoshop makes all the changes to the photo permanent. You can edit the conversion at any time before flattening the image by clicking on the adjustment layer’s icon (circled).

Click on Adjustment Layer to edit

Non-destructive photo editing is always better than destructive editing. The destructive methods are included here for completeness.

 

2. Convert to Greyscale (Destructive)

The simplest black and white conversion method, converting to grayscale discards all the colour information in the photo.

Photoshop CS 5:

1. Image > Mode > Grayscale

Pros: Quick and easy.

Cons: You have no control over the conversion.

Connor at 4 months: Beth Cook
Digitally shot color image converted to Gray Scale in Photoshop CS5

 

3. Use the Hue/Saturation Tool (Non-destructive)

This method gives exactly the same result as converting to grayscale. The only advantage is that it’s available as an adjustment layer, and can be used as part of a non-destructive editing process.

Photoshop CS 5:

1. Layer > New Adjustment Layer > Hue/Saturation
2. Click ‘OK’
3. Move the saturation slider all the way to the left (-100) and press ‘OK’

-OR-

1. Adjustment Layer Palette > Hue/Sauration
2. Move the saturation slider all the way to the left (-100) and press ‘OK’

Pros: Quick and easy and and can be applied as an adjustment layer in Photoshop CS 5.

Cons: You have no control over the conversion.

Kristie in the Clouds: Beth Cook
Digital Color Photograph Desaturated to Black & White

 

 LAB Color Method (Destructive)

This technique converts your photo from RGB mode to Lab mode, which records the brightness and colour values separately, then discards the colour information leaving a black and white image.

Photoshop CS 5:

1. Image > Mode > Lab Color
2. Go to the Channels window if it’s already open (if not go to Window > Channel) and select the Lightness channel
3. Image > Mode > Grayscale
4. Click ‘OK’

Pros: Gives a better black and white conversion than the convert to grayscale and hue/saturation methods.

Cons: Destructive editing process that doesn’t give you much control.

Anne’s Legs: Beth Cook
Digital Color Photo converted to Lab Color

 

 

5. Gradient Map (Non-destructive)

The gradient map tool maps a black and white gradient to the brightness values of your photo. Dark areas become black or dark grey and highlights white or light grey.

Photoshop CS5:

1. Press ‘D’ to reset the foreground and background colours to black and white.

 

 

1. Layer > New Adjustment Layer > Gradient Map
2. Click ‘OK’

Pros: Quick and easy non-destructive black and white conversion

Cons: No control over the conversion

Red Clay Road, Montana: Beth Cook
Digital Color Photo converted to Black & White by Gradient Map

 

6. Channel Mixer (Non-destructive)

The Channel mixer is the first black and white conversion tool listed here that begins to use the full potential of the information contained in the colour photo. Colour photos have three colour channels; red, green and blue. These primary colours combine to make the millions of colours in your photo.

The Channel mixer conversion method lets you adjust the ratios between the red, geen and blue channels. Lightening the value of a channel lightens colours close to it on the colour wheel and darkens the colours that are opposite it. Increase the value of the red channel for instance, and you’ll make the red tones in your photo lighter, and the blue ones darker. This has the effect of lightening skin tones and darkening blue skies.

The Channel mixer is the digital equivalent of black and white photographers using colour filters. Setting the brightness of the red channel to 100% gives the same effect as using a red filter on the lens with black and white film.

Photoshop CS5:

1. Layer > New Adjustment Layer > Channel Mixer (OR, click on Channel Mixer in your Adjustment Layer Palette)
2. Tick the monochrome box.
3. Move the Red, Green and Blue sliders to the left and right to lighten and darken different tones in the photo. The total of the three sliders should be 100% at all times.
4. Click ‘OK’ when you’re done.

San Francisco Bay Bridge: Beth Cook
Digital Color Photograph converted to Black & White with Channel Mixer

There are several more ways to convert color photos to black and white – but I feel like this is a good place to start.

It’s worth taking the time to experiment with these different methods when deciding how to approach black and white conversion. Some may work better for you than others, but always remember to keep an original copy of the image if using a destructive method!