Compositing Quick Tips - The Photoshop: Professional Retouching and Compositing Tips, Tricks, and Techniques - page 297

I've mentioned that observing real life can help tremendously with retouching, and this is
especially true with shadows. Shadows in the real world seem to be made up of two parts:
the contact shadow, where the person or object is in direct contact with a surface, and the
shape shadow that appears because of the light.
There are many ways to add the shape shadow. A lot of times you can do this by creating
a copy of the cutout, filling it with black, and then using Transform and opacity, but there
are times when that won't work.
Here's an equally simple technique you can use, but getting it to look just right will take
plenty of practice—but that's the same with everything you do in Photoshop.
1. Add a new blank layer (Layer > New > Layer), name it contact shadow , and click
OK. Drag this layer below the cutout in the layer stack ( Figure 5.21 ) .
Figure 5.21
2. In the Layers panel, Command/Ctrl-click the layer mask used to create the cutout.
In this example I clicked the layer mask in the children layer, which loads the
cutout as a selection ( Figure 5.22 ) .