How to mix Black & White and Colour

The Black and White feature in Photoshop CS3 allows you to selectively convert a portion of your colour image. Philip Andrews reveals how to do it

B&W with colour
B&W with colour B&W with colour

There are almost as many ways to convert colour photos to black and white as there are photographers. No, really! The aim of most techniques is to provide a level of customisation that allows the monochrome worker the chance to tweak the mapping of colours to greys.

Why is this important? Well, a finely crafted greyscale displays everything from rich blacks to delicate whites with subtly graduated mid tones in between. One problem with conversions from colour originals is that an image that appears to be dynamic and contrasty in colour can become drab and lifeless in B&W. It is only when the photographer can control how the colours are converted to grey that a better quality conversion results. Hence the plethora of techniques!

In Photoshop CS3, Adobe responded to photographers' demands for a better way to convert with the creation of a dedicated feature called Black and White. The controls in this one dialogue enable map-able greyscale conversion with the added bonus of tint options being included. Add to this the fact that Black and White can also be used as an Adjustment Layer, and photographers are now in Monochrome heaven.

In this tutorial we use the abilities of the new feature with some masking techniques to mix tinted mono and full colour in the same image.

Custom Converter
The new Black and White feature provides a powerful way to convert colour pictures to greyscale. The way different colours are mapped to gray can be adjusted with the channel sliders and the tint options can be used to add a colour to the result. The new tool provides all the power of the Channel Mixer without the drawbacks. Overall density of the conversion is handled automatically with reference to image content, so there is no need to watch the channel settings numbers to ensure they add up to 100, as was the case with Channel Mixer.



1 Select the area to remain in colour. Using the new Quick Selection tool you can create a pretty accurate selection of the flower with a few quick strokes. You can add to or take away from the selection that the tool creates using the shortcut keys Shift (add) and Alt/Opt (subtract). You may need to zoom in and change brush tip size to help with accuracy.

2 Next we adjust the edge of the selection using CS3's new Refine Edge controls. Most of these adjustments have been around for ages but in CS3 they have been grouped in a single dialogue along with five preview options for displaying the quality of the edge. In this example the selected area is shown against the rubylith mask (red).

3 Using the Refine Edge tools, ensure the edge between the subject and background is accurate. Now we need to swap the selection from the subject to the background as this is the area of the photo that we are going to change to grey. Do this by choosing Select > Inverse. This background selection will form the basis of our mask.

4 With the selection still active create a new Black and White Adjustment layer (Layer > New Adjustment Layer > Black and White). Automatically the selection creates a mask that shields the subject from the greyscale conversion. Use the colours sliders in the Black and White dialogue to control how each hue is mapped to grey.

 

5 Also included in the new Black and White dialogue is a tinting option. Clicking the Tint checkbox gives you access to the Hue and Saturation sliders. These controls perform just like their namesakes in the Hue/Saturation control. Choose the colour of the tint with the Hue slider and the strength of the colour with Saturation.




6
The beauty of using a mask to control where the convert to grey-scale effect is applied is that you can make adjustments later. Here, the area between the leaves needs to be included in the conversion. By selecting the mask thumbnail in the Layers palette you can use a white soft-edged brush to paint the conversion into non-converted areas.