Channels and selections
To start, find the Color Channel which shows the maximum amount of Contrast in the hair.
Duplicate that Channel and bring up the Levels panel (CMD/CNTL + L). We can bring the black point up to create very intense Contrast in the image. The darks should be extremely dark but be sure not to overdo it! A good way to check is if the edges of the hair look too coarse, you can decrease the darkness a little bit.
All of this is done in the Channels tab, but it needs to be turned into an actual usable selection. Hold CMD/CNTL and click on your Channel copy. This selection will remain, and you are able to go back into the layers and edit from there. Click on the Layer Mask icon, and everything that was dark will turn invisible. All you have to do is Invert the selection (CMD/CNTL + I). If parts of the image are Transparent that shouldn’t be, you can paint over the Layer Mask where it needs to be filled in.
Control that fringe!
To take care of fringing (Light or white part around the edges of the Hair), Clipping Masks will come in handy!
- Create a New Layer
- Right click, and select “create Clipping Mask”
- Use the Brush Tool or Clone Stamp tool to fill in the white areas
Lastly, be sure to change the clipped layer from normal to Darken. This will cause your Brush or Clone Stamp to only effect the whitest parts of the hair.