Black and White Photo Conversion

Copyright 2006 Peter Horner

Most images were produced in black and white for nearly a hundred years after the invention of photography, but now colour images have become commonplace. Creating strong three dimensional images on a piece of paper is one of the best attributes of black and white photography, as the effect can be more striking than with a colour photograph. Without the colour to distract us we become more aware of the subtle tones which can be found within a black and white image. In this article I will share the technique I use that will help you create beautiful, striking and moody black and white images from your colour photographs.

Digital cameras have a black and white mode but more information and detail will be recorded in colour, which will also create a higher quality printed image. This is why I always shoot in colour then convert images later. There are several ways of converting an image to black and white using Photoshop and many other image editing programs. You could simply desaturate the colours, but creating a black and white image with real tone and definition goes beyond this. Levels, curves and the Unsharp Mask can be used creatively with black and white conversion to provide further control over tones and contrast to create a stunning image.

Channel Mixer – I have found that using the Photoshop Channel Mixer is the easiest way to convert an image to black and white and produces the best results. The Channel Mixer allows you to control how much red, green and blue contribute to the final monochrome image.

The Channel Mixer can be selected from the adjustment layer popup menu in the layers palette or you can also access it from under the image menu.

Clicking on the left tick box entitled Monochrome will convert your photograph into a greyscale image, and gives you the ability to blend the red, green and blue channels. Adjust each of the sliders to produce an image to your liking. As a rule make sure that the total values for each channel adds up to 100%. This creates monochrome images that are the equivalent of ones shot on black and white film through red, green or blue filters. For example if you wanted to maximize cloud contrast in a blue sky, then a red filter would achieve this. I usually set the red channel to 0 and the green channel to 100 to cut down on the amount of noise, or sometimes a combination of red and green depending on the image.

Curves and Levels – Brightness and contrast can be adjusted in Photoshop by using the curves and levels tools, which can be found under Image > Adjustments Curves/Levels. Both curves and levels allow you to adjust the tonal range of an image. When using the levels command you can make adjustments to just three variables, highlights, shadows and midtones. I prefer to use curves as it gives you more precision. With curves you can adjust any point along a scale while keeping up to 15 other values constant. By adjusting the black point and white point in curves you can give your image more contrast. At opposite ends of the diagonal line you will find a small dot. When you grab hold one of the dots with your mouse and drag it around you will see the image change. To create more contrast drag the black point lower and the white point higher, so that either end of the diagonal line is curved. Practice using curves and levels and explore the different effects you can achieve with your images.

Unsharp Mask – The Unsharp Mask is my preferred tool for sharpening images, which can be found under Filter > Sharpen > Unsharp Mask. It is a traditional film compositing technique used to sharpen edges in an image and corrects blurring. The Unsharp Mask locates pixels that differ from surrounding pixels by the threshold you specify and increases the pixels’ contrast by the amount you specify. In order to get the look which I desire in my images I use the Unsharp Mask twice. I begin by using a high radius and lower amount, such as a radius of 50 pixels and an amount of 30%. This gives the image a much more intense look and details will stand out. The second time I use a lower radius of 1 pixel with a higher amount of 30%, which will correct any blurring and sharpen the image.

Visit this page to view examples of images created using a combination of these techniques –