This filter is derived from the “3D Outline” script
( → → →
in the image window), which creates a logo (see above) with outlined text and
a drop shadow.
The filter outlines the non-transparent areas of the active layer
(determined from the Alpha channel) with a pattern and adds a drop
shadow.
Here, we will use the alpha term to refer to these
areas of the active layer defined by the non-transparent pixels.
The filter uses the Sobel edge
detect filter to get the alpha's outline. So with a simple alpha,
for example a cleared rectangle selection, you will just get the
boundary. But when you use a layer mask (don't forget to Apply the
Layer Mask), as in the following example, the edge detector will find
more edges and thus the filter effect will be applied to these edges
too.
![[Warning]](images/warning.png)
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Warning |
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The image will always be resized to the active layer's size.
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16.2.2.
Activate the filter
This filter is found in the image window menu under
→ → .
The filter only works if the active layer has an alpha channel.
Otherwise, the menu entry is insensitive and grayed out.
