Post Reply 

Alpha channel from inverted selection

Aug 31, 2014, 17:58
Post: #1
Alpha channel from inverted selection
I have a 2D logo. I want to create an alpha channel around the base image. I have tried all manner of combinations of inverting selection, etc., but cannot get GIMP to just fill the blank space with alpha channel. Do I really need to do this manually pixel by pixel with the eraser tool ?
Find all posts by this user
Quote this message in a reply
Aug 31, 2014, 18:29 (This post was last modified: Aug 31, 2014 18:29 by rich2005.)
Post: #2
RE: Alpha channel from inverted selection
(Aug 31, 2014 17:58)WhyDoIHaveToCreateAnAccount Wrote:  I have a 2D logo. I want to create an alpha channel around the base image. I have tried all manner of combinations of inverting selection, etc., but cannot get GIMP to just fill the blank space with alpha channel. Do I really need to do this manually pixel by pixel with the eraser tool ?

You have to create an account in order to contribute (in your case post) to the forum. This is not UseNet. Believe me, it is a lot easier here than on other forums

Back to the question. Depends on the logo.

Does your image have an alpha channel to start with?
Gimp menu Layer -> Transparency -> Add Alpha Channel
If that is grayed-out there is one. Then with a selection Edit -> Cut should remove something. If the wrong part invert the selection.

If the logo has a single colour background then a simple color-to-alpha should work Gimp menu Colors -> Color To Alpha.
see: http://docs.gimp.org/2.8/en/plug-in-colortoalpha.html

Or make a selection using one of the selection tools and apply some principles. see: http://gimpforums.com/thread-proper-subj...-painting?

If the background is complicated then sometimes a layer mask is the way to go see: http://docs.gimp.org/2.8/en/gimp-layer-mask-menu.html and subsequent pages.

If your logo is not too controversial and you have worked through the above to no avail, then post it to get further advice.

** https://www.gimp-forum.net/ now answering questions**
Find all posts by this user
Quote this message in a reply
Aug 31, 2014, 18:30
Post: #3
RE: Alpha channel from inverted selection
The first thing to do is to make sure your layer has an alpha channel.
Layer > Transparency > Add alpha channel
(Or you can do it the Layers window. Right click the layer and select Add Alpha Channel. The layer name is in bold if it does not have an alpha channel.)

Now make your selection. Invert the selection if necessary.
Now do Edit > Clear
(or press the Delete key)
Find all posts by this user
Quote this message in a reply
Aug 31, 2014, 19:12
Post: #4
RE: Alpha channel from inverted selection
Cheers, TY for the assistance. Sorry for my tone. I was rather frustrated.
Find all posts by this user
Quote this message in a reply
Post Reply 


Possibly Related Threads...
Thread: Author Replies: Views: Last Post
  Transforming a selection on a layer pdev 1 43 Aug 8, 2017 05:07
Last Post: ythgilb
Wink Use area selection as a template to another area eduardolucioac 2 75 Jul 31, 2017 17:31
Last Post: eduardolucioac
  remove alpha channel on export? peekofartertainment 1 103 Jul 22, 2017 08:08
Last Post: ythgilb
  Color to alpha really weird Sagemode 14 519 Sep 16, 2014 05:49
Last Post: Sagemode
  Histogram of same selection in two images Itchtakov 2 333 Aug 29, 2014 15:16
Last Post: Itchtakov

Forum Jump:


GIMP ForumPortalArchiveContactTermsRSS