 Sometimes it can be very difficult to extract a model from the background of an image when the model has curly or frizzy hair. This Tutorial demonstrates one way to make this type of extraction using an alpha channel mask.
This technique works best with portraits of curly or frizzy haired models shot against a light or white colored background.
I chose to use the Alpha Channel Extraction method with this particular image because I needed to make careful and accurate changes without tarnishing the quality of the photo. The changes to the photo are (visually) subtle. However, I am working with a very high-res file and this method will work great for the detail needed in a large-scale format. Here is a before and after:
Use this image!
 Step 1:
Open the image you will be using for this tutorial. Unlock the background layer by double clicking on the layer. Give it a name.
 Step 2:
Select the blue channel (or the channel with the most contrast between the hair and the background) by clicking on it. Turn off the visibility on the other channels.
 Step 3:
Navigate to Image > Calculations under the drop down menu. In this example we used "Soft Light" for the Blending mode. Make sure next to Result, you have "New Channel" selected. Hit OK.
Your image should look simialr to the following:
Step 4:
Using the lasso tool with a feather of zero, carefully select the model from the background. When selecting around the model's hair, keep the selection just inside the frizzy part. Be sure the selection does not overlap onto the background. This will leave you with a rough lasso around the hair and a good lasso around the face, neck and clothing.
Step 5:
Fill the selection with solid black. Your image will look like this:
Step 6:
Select the inverse by navigating to Select > Inverse from the drop down menu. With the Lasso tool, deselect ONLY the area around the frizzy hairline so that the background is selected except right around the hair.
Fill the selection with solid white. Deselect. Now you will have a black and white silhouette of the model with a strange-looking halo around the hair.
 Step 7:
Use the dodge tool to go over the frizzy hairline. Set the Range to Highlights and the Exposure to 100%. This step will help separate the background from the hair by making it solid white. This step will also remove small stray hairs.
Step 8:
Select the Burn tool. Set the Range to Shadows and the Exposure at 100%. Now go over the hairline again. This time, the whites will remain white, but the hair will turn solid black.
*When you are finished with steps 7 and 8, you should have something that looks like this; a crisp black and white silhouette of the model with no shades of gray.
 Step 9:
Select the RGB channel and turn off visibility on the Alpha 1 channel (silhouette). Navigate to Select > Load Selection under the drop down menu. Select Alpha 1 beside Channel and make sure new Selection is checked. Hit OK.
Step 10:
Navigate to Select > Feather... from the drop down menu and enter 2 pixels.
Step 11:
Navigate to Edit > Clear.
The background disappears and voilą! You have one really beautiful extraction!
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