Selections and Cutouts - The Photoshop: Professional Retouching and Compositing Tips, Tricks, and Techniques - page 47

Tip
To clearly see the new hair you are painting/smudging in, add a blank layer, fill it
with white (Edit > Fill, and choose white from the Use menu), and drag it be-
neath the layer containing the cutout; just as in the earlier example faking the
cutout of the chimpanzee.
Tip
Vary the Strength and Size settings of the Smudge tool as you work around the
hair to create a more random and believable effect. You could also create several
more brushes and use them in combination to enhance the result.
Advanced Blending
The Blend If sliders can do more than I have space in this topic to explain. I tend to use
them for controlling how color appears within the highlight and shadow areas of a picture,
and also for extracting colored liquid.
Here's how they can be used to extract colored liquid, in this case coffee, from its original
background. Figure 1.53 shows the final image.