2011

If you want to change the format settings of a layer, you must create a new
layer and start over.
Adding, Deleting, Clearing, and Wiping Layers
All layers appear in the Layers list. The Layers list allows you to view and
rearrange layer ordering in the Paint node, as well as select layers to be hidden
or revealed.
Layers can be internal or external to the Paint node. An internal layer is a
transparent layer that can only be added from the Paint node. It can be used
to create, for example, an alpha.
An external layer does not originate from the Paint node. It can be an image
and can include a front and/or alpha. An external layer is connected to the
Paint node by means of a Layer node, whereas an internal layer needs no such
connection since it originates with the Paint node. A common reason for
adding an external layer is to touch up an image's front or alpha. When you
paint on an external layer, you are compositing strokes onto the incoming
image. This makes it possible to change the incoming image without losing
your strokes.
When you add either an internal or external layer, it goes to the top of the
Layers list. The order in the Layers list reflects the layer order on the canvas.
The topmost layer covers the image data of the underlying layers. Layers can
be hidden or rearranged within the Layers list.
When you delete a layer, it is removed from the Layers list. When you clear
a layer, it remains in the Layers list but all strokes are removed.
Adding a Layer
When you add an internal layer, it includes both a layer front and a layer
alpha. When you add an external layer that only includes the front, a black
layer alpha will automatically be created.
574 | Chapter 24 Raster Paint