Quick Transparency Tip for the Gimp

I just learned something new about the Gimp. I guess this should have been obvious. If you've ever editted a picture in the Gimp that has no transparency, like a JPEG for example, then you know that when you erase, it always erases to the background colour. This makes sense in general, but I've in the past I've had to go to a lot of work to get transparency while I'm working. I'd do it by saving as an XCF (the Gimp's native file format) then adding a layer with a transparent background and cutting and pasting the whole picture into the new layer. Don't do that. The right way is to just add an alpha channel to the background layer. You might still have to save as XCF, but the extra manipulation is unnecessary. Just right-click the layer in the Layers dialog and pick "Add Alpha Channel." It sounds obvious, alpha is the same thing as transparency. The reason I never figured it out before is simply that when you create a layer or new picture, the Gimp refers to it as the background being a colour or transparent, not an alpha channel.

Anyhow, hope this helps someone.

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Thanks! This tip just saved me a bunch of time.

Nice tip! I've read about this b/4 somewhere else; but the instructions were a little vague. Since I'm a GIMP newbie, your tip worked out great for me.

thanks for the alpha channel tip

thanks man, worked like a charm on this difficult TIFF

It's funny but I was just ran in to this again the other day after not doing it for a while. I added another layer I didn't need again - old habits die hard.


Thanks a bunch!!

Thanks a lot, I just wasted half an hour searching for a way to erase a selection to transparency. Thanks god i had the idea to google it int time. again thanks a lot for sharing this big tip.

Yeah, same... first time seriously trying the GIMP after working professionally with Photoshop for a couple years. So far there've been a few really awful things like this, that cross the line from being different to being just plain wrong.

Hassle, definitely, but I wouldn't call it "wrong". If they erased to transparent in a format that doesn't support it then that would be the wrong thing for another whole bunch pf users. Maybe a setting for the eraser tool that automatically added a transparent background layer would be nice though.

same thought here........ just made a new shorcut for add alpha......