[Bug 41759] "Alien Glow" effect crops too tightly

[era]

Public bug reported:

Affects: gimp (Ubuntu)
       Severity: Normal
       Priority: (none set)
         Status: Unconfirmed


Description:
Creating a simple text logo with this effect with the default parameters
(150-pixel glow) creates an image which has a very visible bounding box.

http://laku19.adsl.netsonic.fi/~era/tmp/fnord.png is a quick example.

1. Create a new GIMP document with suitable dimensions, something like 256x92 pixels
2. Type some text in a suitable typeface and size
3. Apply the effect: Script-Fu > Alpha to Logo > Alien Glow
... I selected a different color but kept the 150-pixel radius
... Notice how as the last step, the plug-in effect crops the image to much smaller than it was
... Optionally, you can even resize the canvas to a bigger one after the plug-in finishes, but unfortunately, this does not reveal the cropped parts -- they are gone for good
4. Delete the background layer so only the original text layer and the Glow layer remain

Desired result:

An image with "glowing" text suitable for inclusion on a web page
without disturbing artefacts

Actual result:

The cropping of the "glow" color makes it very clear that you are
looking at a distinct image; the bounding box of the image are very
clearly discernible. The illusion of a piece of glowing text on a page
is simply not there because the glow does not gradually fade to the
background of the page.

This is in Gimp 2.0 on stock amd64 Breezy.

-- 
"Alien Glow" effect crops too tightly
https://launchpad.net/bugs/41759