There are many reasons why you may want to change hair color in Photoshop. Perhaps your subject has recently dyed their hair and it doesn’t look natural. Perhaps you want to see what you would look like with dark hair.
Changing Hair color in Photoshop is much easier than doing it in real life and by the time this tutorial is over you will be on your way to color city!
It is much easier to make hair dark than light. If you are starting out with a blonde and want to make her a brunette, not too hard. Turning black hair into blonde hair is nearly impossible. The reason is that you have more information to start with in lighter colors. With black you will see very little detail, making it difficult to make lighter colors realistic. Also be sure to not over-saturate hair color, there is a big difference between yellow and blonde.
Just sit and watch this video tutorial by Phlearn and you will find a lot of useful tips and techniques that will help you master the most difficult hair color changing situations in no time.