A free tutorial on using Color Range selections in Photoshop for picking out colour to swap it for another
Before image from www.Sxc.hu
Find the Color Range option inside the Select menu at the top of Photoshop. As this is not strictly a tool, you won’t find it in the Toolbar. But if you have the Marquee, Magic Wand or Quick Selection tools at hand, Ctrl/right-click over your image to see Color Range listed.
First, choose how you want to sample the colour on your subject. Click on the Select list and try one of the colour options. The white areas in the preview represent the selection, but if this is too faint, set Select to Sampled Colors to do things manually.
To select a colour in just one area without affecting the rest of the image, tick the Localized Color Clusters option. The Range slider should now be visible, as well as Fuzziness. Set Range to 20% and Fuzziness to 100 to begin with.
To make a selection, click on the colour in your image that you want to alter. All of the areas in your chosen colour should show up on the preview in white. Start from the edge of the colour and a small area of white should show inside Color Range.
With the selection started, click on the eyedropper with the plus symbol. On your image, click and drag from where you left off to continue to add colour to the selection. More white should now appear inside the preview. Don’t worry if the white area bleeds over to other parts of the image.
Now click on the eyedropper icon with the minus symbol. Using the preview in the menu as a guide, click over the extraneous white areas. This will tidy up the selection even more. You can alter the Fuzziness and Range sliders for further refinement. Hit OK to apply the selection.
With a selection of just the colour, adjustment layers such as Hue/Saturation can be added via the Layers palette. Notice how the adjustment layer uses the selection for its mask, meaning that you can change hue of this colour only for a creative effect.