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Removing alpha channel

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Removing alpha channel
AncientxFreako Offline
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#1
03-15-2021, 10:43 AM
I've recently had some issues with GIMP generating alpha channels after editing images when using layers. Upon exporting to .png, the alphas get left in. I'm being told by an ace programmer that this is a ridiculous thing that GIMP should not do. I really, really like GIMP, and would rather continue using it. Is there an update that deals with this without a plugin?  And btw, I haven't seen a good plugin that even does decent batch alpha removal.
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rich2005 Offline
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#2
03-15-2021, 12:49 PM (This post was last modified: 03-15-2021, 12:49 PM by rich2005.)
Quote:..snip.. Upon exporting to .png, the alphas get left in...

Flatten the file before exporting, that gives a png without an alpha channel.

Looking at your other posts you seem to be looking for a batch method. Is that correct ? Is this for animations or individual files ?
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Ofnuts Offline
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#3
03-15-2021, 01:02 PM
(03-15-2021, 10:43 AM)AncientxFreako Wrote: I've recently had some issues with GIMP generating alpha channels after editing images when using layers. Upon exporting to .png, the alphas get left in. I'm being told by an ace programmer that this is a ridiculous thing that GIMP should not do. I really, really like GIMP, and would rather continue using it. Is there an update that deals with this without a plugin?  And btw, I haven't seen a good plugin that even does decent batch alpha removal.

Always easier to remove something unwanted than to recover something that has been removed too early.

When you export a PNG, you can specify formats without alpha channels (RGB instead of RGBA). In addition if you don't need the alpha channel, one can assume that the image is fully opaque and therefore the alpha channel is 255 everywhere, in which case the PNG format compresses it very well and the size increase due to the alpha is minor ( a few percent).

PS: real ace programmers are too clever to make blanket statements.
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Blighty Offline
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#4
03-15-2021, 03:58 PM
(03-15-2021, 10:43 AM)AncientxFreako Wrote: Upon exporting to .png, the alphas get left in.

I don't really understand what you mean by "the alphas get left in".

In the png export dialogue you can uncheck Save background color.
The transparency will be retained, but the transparent pixels will be black. Thus not possible to recover original pixel colors.
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