Unapply Alpha Channel - Printable Version

Unapply Alpha Channel - Printable Version

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+--- Thread: Unapply Alpha Channel (/Thread-Unapply-Alpha-Channel)

Unapply Alpha Channel - ShynnSup - 08-25-2022

Hi everyone,

I exported an image from a rendering software which had an option to 'apply alpha channel'. By mistake I enabled this option and later realized all my images had no sky background.

While viewing the images in photos (Windows) I noticed the background would show for a split second before Photos applying the alpha...

I opened the image in Gimp and when I unticked alpha channel, Voilà, the background was recovered.

Problem is... I can't export it for some reason... when I save as PNG the background is back to transparent, and when I save as JPG it is all white... but that is not what I am seeing in my GIMP window...

When I run Layer > Transparency > Remove Alpha Channel. I do get the white background preview.

RE: Unapply Alpha Channel - PixLab - 08-25-2022

Try the Erasor Tool but in the Tool Options tick the Anti erase mode and paint over your sky (big size brush to go faster), the sky should come back

[Image: nWzg6X7.png]

Then when you export (don't over write the original) untick the Save color values from transparent pixiels

[Image: 78rw7q2.png]

RE: Unapply Alpha Channel - ShynnSup - 08-26-2022

This worked perfectly, thank you!

RE: Unapply Alpha Channel - rich2005 - 08-26-2022

@ShynnSup pleased you got it fixed.

A bit surprised this does not come up more often.

Quote:When I run Layer > Transparency > Remove Alpha Channel. I do get the white background preview.

What you get is the current background colour, as shown in the FG/BG swatch, replacing transparency. This can be useful, some colour other than white.

Quote:... opened the image in Gimp and when I unticked alpha channel, Voilà, the background was recovered.

Almost there Wink

After disabling the Alpha Channel;

Go back to the layers dock and apply Layer -> New from Visible
Now, to tidy up, use Layer -> Transparency -> Remove Alpha Channel.

30 second example: https://i.imgur.com/vKHSRV6.mp4

Edit: Not quite applicable but a good quote anyway. IBM 1978

If it's there, and you can see it, it's real.
If it's not there, and you can see it, it's virtual.
If it's there, and you can't see it, it's transparent.
If it's not there, and you can't see it, you erased it.