HSB and Color Modes

HSB and Color Modes

The Hue, Saturation, and Brightness modes each combine
one of these values (H, S, or B) from the foreground layer
with the other two from the background layer. Color takes
both the hue and saturation from the top layer, using only
the luminance (or brightness) from the underlying background.

These modes are often useful at an Opacity setting below
100%, to combine source HSB values with ones that you
choose.

Stencil, Silhouette, and Preserve Transparency

Commonly overlooked, Stencil and Silhouette blending
modes operate only on the alpha channel of the composition.
The layer’s alpha or luminance values become a
matte for all layers below it in the stack. Stencil makes the
brightest pixels opaque, and Silhouette the darkest.
Suppose instead you have a foreground layer that is meant
to be opaque only where the underlying layers are opaque,
as in Figure 3.33. The small highlighted checkbox, labeled
Preserve Underlying Transparency, makes this happen,
much to the amazement of many who’ve wished for this
feature and not realized it was already there.