Ask Ubuntu is a question and answer site for Ubuntu users and developers. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

How can I make part of the image transparent? I tried the "Color to alpha" option in GIMP, but it's not working.

I know in Photoshop you can erase the part you don't like, and make it transparent. Does GIMP support that?

share|improve this question
On 13.04/3.10.10 installed with apt, [this answer][1] worked easiest for me. [1]: – user128334 Sep 8 '13 at 16:44
up vote 53 down vote accepted

In GIMP layers can either have an alpha channel or have no alpha channel. When you try erasing parts of an image when there's no alpha channel you get backround color.

To add an alpha channel you can bring up the Layers dialog by pressing Ctrl-L, right-click on the layer you want to edit and select Add Alpha Channel there.

enter image description here

From there everything is very much like in Photoshop - i.e. Eraser tool erases to transparency, you can make a selection (using, for example, Magic Wand tool) and erase everything in it by pressing Del, etc.

share|improve this answer
+1 for add alpha channel – warl0ck Apr 8 '12 at 12:22

If you use an eraser, that will erase to transparence. You also can select an area and press the delete key (not backspace)

share|improve this answer
Without a transparent layer , it becomes white , I guess it's default background color ;-P – warl0ck Apr 8 '12 at 12:24
You can delete the background in the same way – pbfy0 Apr 8 '12 at 12:31
I can't believe. It worked so well. Thank u. :) – Akira Aug 13 '13 at 6:54
@warl0ck It defaults to secondary color – PeterM Jun 30 at 18:49

I think what you want to so is as follow: You blur a layer (eg image of a face) and want to remove the blur from detail areas (eg eyes, lips, eyebrows). Add alpha channel to the blur layer as suggested above, then hold down Alt as you use the eraser tool, and it will remove the effect only from the erased area. Then turn down the layer opacity until you get a just perceptible softening of the features with sharp details (eyes, lips, etc).

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.