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Getting Anti-aliasing working with an alpha layer

Sep 3, 2011, 21:01
Post: #1
Getting Anti-aliasing working with an alpha layer
Hi everyone,

So I have this small image consisting of a sine:

[Image: sleepingIcon.gif]

and I would like to get a gradient border on it (something like two pixels would be perfect) from the green sine to black.
(Partial transparancy would be nicer but since .gif doesn't support that...and yes I do need it to be a .gif XD)

Problem is...that I can't get any of the filter options to work, they are all disabled. After some tests I noticed that this is because there's an alpha layer that for some reason disables the filters.

So...how to get a gradient (green to black) border on the sine?

thnx in adance,

Reskaillev
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Sep 3, 2011, 23:05
Post: #2
RE: Getting Anti-aliasing working with an alpha layer
While you image is still RGB (important!)

- Set the background color to match the future background of your GIF (black, in your case)
- Layer/Transparency/Semi-flatten will then add antialiasing for your specific background (ie, replaces partially transparent pixels by an opaque pixel of the color obtained by putting the partially transparent one over the background color).

You can then convert to indexed and save as GIF.

Now answering your questions on
https://Gimp-Forum.net
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