
Selections and Transformations 565
3 Select the area that you want to subtract.
If you are using the Oval Selection tool or the Rectangular Selection tool ,
you can select a circular or square selection by holding down Shift while dragging.
You can also subtract from a selection by holding down Option (Mac OS) or
Alt (Windows) and selecting the area you want to subtract. If you are using
the Oval Selection tool or the Rectangular Selection tool and you
want to select a circular or square area, you need to hold down Option +
Shift (Mac OS) or Alt + Shift (Windows) while dragging.
Subtracting from a path-based selection.
You can also load selections from the Selection Portfolio, a library of ready-to-use
selections. In addition, you can use Boolean operations to combine existing selections
with alpha channels.
Preparing selections for transformations
Before attempting to transform a selection, it’s important to determine if it’s path-based
or pixel-based because the selection type determines which transformations you can
perform. For example, path-based selections support many transformations that pixel-
based selections do not. However, you can convert a pixel-based selection to a path-
based selection to apply transformations to it. For more information, see “To convert a
pixel-based selection to a path-based selection” on page 549.
To prepare a selection for a transformation, you can set the reference point around which
the transformation is performed. The reference point is located at the center of the
selection by default.
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