Surprisingly we do this by using a Black & White adjustment layer. This allows us to break our image down to primary colours, so that we can then start enhancing specific parts of our images within a particular colour range. If it sounds complex, after 2 minutes of this video you will see that it is, in fact, very simple!
Quick Photoshop Secrets 2: How To Make Precise Adjustments Based On Colour
Article By Jimmy McIntyreIn the second video in this series of Photoshop Secrets, we look at how to make very precise changes to your image based solely on colour.