Learn this powerful technique to change hair color in Photoshop!
Keep in mind that when doing hair color changes in Photoshop it is a lot easier to go from light hair colors to dark. The biggest reason is that lighter hair tends to have more detail and therefore you can make those areas darker and keep the detail.
Going from dark hair to light hair is much more difficult. For example, turning black hair into blonde hair is extremely difficult or impossible in a lot of cases because the details are lost in the shadows, and photoshop cannot recreate the detail that was lost.
Keep in mind is that everyone's hair color is different. The numerical values for any adjustments that I use on this photo may not work for your photo. Use my values as a starting point, and adjust accordingly for your image.
The techniques in this video are all non-destructive which means you can always come back and edit them!