Preserve selective colours in a B&W conversion

5 Black and white

Choose Layer > New Adjustment Layer > Hue/Saturation to create a second adjustment layer floating above the first one. Leave this new adjustment layer set to Master, then drag its Saturation slider left to -100 to remove all traces of colour.

6 Invert the mask

Click on the Hue/Saturation 2 adjustment layers’ white mask to select it. In the Properties panel, click Invert to turn the white mask to black. The black mask temporarily stops the monochrome adjustment layer from desaturating layers below.

7 Remove unwanted reds

Grab the Brush tool. In the Brush Preset picker, choose a soft round tip of 250 pixels. Set the foreground colour to white. Click the black adjustment layer mask; brush the white tip over unwanted traces of red until only the bus and flags have colour.

8 Non- destructive editing

As you’re using a mask to hide unwanted traces of red, you are working non-destructively. If you accidentally spray over a flag or bit of bus and desaturate it, press X to change the brush tip to black and brush over the area to restore its red colour.

9 Camera Raw

You can also add the selective colour effect to a JPEG by going to Filter > Camera Raw Filter to open the image in the Camera Raw editor. Click on the HSL/Greyscale icon. Click the Saturation tab, reduce unwanted colours to a saturation of -100.

10 Adjustment brush

To remove traces of red reflecting in the seagull’s feathers, grab the Adjustment brush. In the Adjustment Brush panel, set saturation to -100. Run the brush over unwanted traces of colour until only the iconic phone booths remain red.