Black and white photos with a colored element in it, so-called color key photos, were already popular in the 1980s. After that it became a bit quiet around these pictures. But with the possibilities of digital image editing, the subject has become more popular again. There are several ways to include a color element in an otherwise black and white photo. Today we would like to introduce you to a method that you may not know yet.

The “classic” methods

Before we show you the “Quick & Dirty” method, here are the two most important classic methods using the featured picture as an example:

1. Selections and layers
  1. first, the bus is selected using the various selection tools
  2. the finished selection is copied to the clipboard and pasted as a new layer above the background layer
  3. the background layer is converted to black and white using the black and white tool or the channel mixer
2. Adjustment layers and layer masks
  1. an adjustment layer “black and white” or “channel mixer” is placed on the background layer
  2. using a layer mask the adjustment layer in the area of the bus is made transparent, so that the colorful bus on the background layer becomes visible

The second method is much more flexible than using selections thanks to the layer mask, which can be changed at any time, and should therefore be preferred.

Quick & Dirty

If things have to be done quickly and highest precision is not absolutely necessary, one possibility is to use the so-called history brush. If you don’t yet know this tool you should give it a try. Therefore we want to introduce it here using it to make a color key image.

In the first step, we convert the image as usual with the black and white tool or the channel mixer into black and white.

The Black & White Tool in Photoshop

When you are satisfied with the grey values of your image, click “OK” (who would have thought that?). Then select the History Brush (see the screenshot below).

History Brush Tool

As with all other brush tools, the diameter and edge hardness of the history brush can be adjusted. Start with a relatively large and soft brush. With the left mouse button pressed down start brushing in the area of the bus. And lo and behold, as if by magic, the original colours reappear (Attention: the brush must not be used too close to the edge of the bus, otherwise parts of the background will also become coloured again):

Using the history brush

The protocol brush partially restores the state before the black and white conversion (or other image processing). In this case, the color image is displayed again in those places covered by the history brush.

For the edges of the bus you should use a smaller and harder brush and carefully work along the edges of the object:

Working on the edges of the bus

Especially working on the edges is much more precise and faster with a graphics tablet than with the mouse. But with a little practice and the necessary caution, the work can be done with the mouse.

You see, it can be quite simple. But it should be obvious that you can’t really work on complex shapes with a lot of details with using the history brush.In those cases adjustment layers and layer masks are the way to go.