Fairytale Scene - The Photoshop: Professional Retouching and Compositing Tips, Tricks, and Techniques - page 454

Figure 9.54
6. We need the Inner Glow layer style to show only in certain areas. Go to Layer >
Layer Style > Create Layer, and then drag this new layer to the top of the layer
stack (if you don't it will appear darker because it would be below the Levels ad-
justment layer that we used to darken the children).
7. Add a black layer mask by Option/Alt-clicking the layer mask icon at the bottom
of the Layers panel. Then with a white soft-edged brush, paint to reveal the Inner
Glow effect in areas where you think it would be—assuming that the glow had
been cast by light coming through the gap in the wardrobe door ( Figures 9.55 and
9.56 ) .