Knocking Out Using Channels
Our first example (and my favorite cuz it takes nothing more than Photoshop and some knowledge) of knocking out Hedda uses channels. Most people have seen the channels roll-out and few people use them. We'll be creating new channels and using them as masks.
Here's Hedda, posed against our green
screen. In working with this photo, I realized that I should have had
more light at the top of Hedda's head. Remember, flat lighting is the
key. We'll go ahead and work with this image to show that the techniques
can be used on less than perfect images.
Do a CTRL-A to copy all and a CTRL-V to
past the image onto a new layer. Turn off the background layer.
Click on the circle at the bottom of the
layers pallette and choose 'Channel Mixer' as shown.
The Channel Mixer control panel that pops
up has a check box for 'Monochrome' at the bottom . We are trying to
achieve maximum contrast between the background and the subject. Adjust
the sliders, trying to make the foreground black and the background as
light as possible without losing the details. Watch the hair in the
bottom left corner in our example as we go through this tut. It doesn't
have to be perfect, we'll work on it more in coming steps.
Repeat the steps above to create another
Channel Mixer layer, this time, use different settings to try and keep
the highlights in the hair. don't worry about the subject proper, just
concentrate on the edges. Try to get as much contrast between the two
areas as you can.
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