Selecting fly-away hair can be one of the
toughest assignments in Photoshop. The Extract command can be
helpful. Third-party plug-ins, such as Mask Pro
(www.extensis.com) and KnockOut (www.corel.com), are great.
But sometimes the easiest way to select those random strands
of hair is right in your Channels palette.
Open the image in Photoshop. Open the Channels palette. Click
on each channel, one at a time, to find the channel with the
greatest contrast between the strands of hair and the
background behind them. (Ignore the rest of the image, you're
only interested in the area around the individual strands of
hair.) In our sample image (PhotoSpin.com, #0770118), the Blue
channel offers the best contrast.
We'll duplicate that channel by dragging it to the New Channel
button at the bottom of the Channels palette. With the Blue
copy channel active in the Channels palette, we can use Levels
or Curves to maximize the contrast. Again, we're interested
only in the fringe strands of hair. (Note that I've used the
command Window> Arrange> New Window for [image name] to open a
second window for the image, in which I've zoomed to monitor a
specific area of the image.)
Using the Lasso tool and the Fill command, in combination with
the Brush tool and the Eraser tool, we can easily fill in the
subject and delete the remaining areas of the background. (In
the upper window, only the Blue copy channel is active and
visible. In the lower window, only the Blue copy channel is
active, but all channels are visible.)
When the mask is complete, click on the composite channel at
the top of the Channels palette to make it active, then
Command-click (Mac) or Control-click (Windows) on the mask
channel (Blue copy, in this example) to load the channel as a
selection. You can delete the background, fill it with color,
or invert the selection and copy the subject, ready to paste
into another image.