Changing hair color - part 1

I'm going to use a pretty simple way of not only selecting the hair, but also to change its color. Remember that each picture will have different problems to solve. The professionals always shoot their subjects against a solid color backdrop (usually green). We don't have this luxury, so we'll have to improvise. The first step is to select the hair (duh!). We could use the pen tool, but in this case (and with strands of hair all over the place), the quick mask tool will be a better bet. Hit 'B' on the keyboard to select the brush tool, right click, and from the menu that appears move the slider so that we have a soft brush (0% hardness). Now hit 'Q' to enter Quick Mask. Start painting over the hair. NOTE: We're not really painting so don't panic.

Carry on 'painting' over the hair. When you get to the white coat just paint over it. I'm going to show you a trick in a minute.

When all the hair has been covered, hit 'Q' again to exit the Quick Mask mode. IMPORTANT! We haven't selected the hair! Before you call me a liar and a time waster, let me explain. What we have done is to mask the hair, so that part is the only bit that isn't selected. To invert the selection, just hit 'SHIFT+CRTL+I'. Ok, now hit 'CRTL+J'. This copies our selection and pastes it onto a new layer. One last job here: Hide the background layer by clicking on the little eye to the left of the layer.

Now let's get rid of that white coat. Select the lasso tool 'L' and draw around the white part like this:

Now whatever we do to the layer, only the bit selected will be affected. Now click the CHANNELS panel tab. You'll see four layers; RGB, Red, Green and Blue. Click each in turn and take care to see which has more contrast. In this case, the blue has. Drag the Blue layer over the 'create new layer' icon. Now hit 'B' for the brush tool, and change its mode to OVERLAY and lower the Opacity to about 60%. Slowly paint over the bits that aren't hair.