Selective Colour adjustment

Apply this adjustment via the Adjustment button on the Layers panel or via Layer > New Adjustment.

The following settings can be adjusted in the dialog:

Colour—determines the colour to be adjusted. Select from the pop-up menu.
Relative—when selected (default), colour is added or subtracted in proportion to the amount of that colour present in the source pixels, giving a more natural effect. If this option is off, colours are added or subtracted based on the absolute percentage specified, regardless of the how much of that colour is present in the image.
The sliders control the levels of the named colour in the selected Colour. Drag the slider to the left to decrease the level of the named colour, drag the slider to the right to increase it.