From: Claus Cyrny [mailto:[EMAIL PROTECTED]
Sent: Mon 2/12/2007 11:44 PM
To: Germain Le Chapelain
Cc: gimp-user@lists.XCF.Berkeley.EDU
Subject: Re: [Gimp-user] Copy the alpha channel from an image to another
> > Hi,
> Germain Le Chapelain wrote:
> >  
> > Hi,
> >
> > I feel like my question might be very stupid :
> >
> > I would like to know who to copy the alpha channel of an image to
> > another image.
> Simpy select the alpha channel with 'select all' ([CTRL]+A)
> and copy it into the clipboard. Then go to the second image
> where you want to insert the alpha channel, select the image
> ([CTRL]+A again), and copy this selection into an alpha channel
> ('Select > Save to Channel'). Then just select this new alpha
> channel in the 'Layers/Channels' menu and paste the alpha channel
> ([CTRL]+A, [CTRL]+H) from the clipboard into it. That's all.

Thanks for the explanation.

I might have some serious psychotechnic problems but I am not able to
reproduce the scenario you describe.

However, I have finally been able to do what I wanted from the begining : copy 
paste the all 4 channels from an existing image to a new image.

To do so :

  o when creating a new image, choose 

      `advanced options > Fill with : Transparency' 
    this is what tells gimp that there will be an alpha channel.

  o then you can go select-all => paste in your new image.

But creating a new image, RGB, filled with white, and then adding an
alpha channel doesn't allow to copy all four channel at once, and leave the 
alpha channel at 255.

Similarly, the equivalent script 

  (drawableDst (car (gimp-layer-new imageDst newWidth newHeight RGBA-IMAGE 
"dest" 100 NORMAL-MODE))))
  (gimp-drawable-fill drawableDst TRANSPARENT-FILL)
  (gimp-edit-copy (car (gimp-image-get-active-drawable image)))

Does copy the four channels at once, whereas going 

  (drawableDst (car (gimp-layer-new imageDst newWidth newHeight RGBA-IMAGE 
"dest" 100 NORMAL-MODE))))
  (gimp-drawable-fill drawableDst TRANSPARENT-FILL)
  (gimp-edit-copy (car (gimp-image-get-active-drawable image)))

Leave also the alpha channel to 255.

I don't understand that behavior. : /

Thank you again for your help, I ll get back to that email if I need
to transfert the alpha channel independently !

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