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add an alpha map

Mar 24, 2014, 17:59
Post: #1
Star add an alpha map
Hi,

I created a cloud difference filter and I am trying to duplicate the cloud image and to use that duplicate as an alpha channel to kind of mask the black areas and let the white areas show, a little like we would use an alpha map in the 3d programs.

I searched in the web some tutos and in forums but still couldnt manage to change the alpha channel.

any help would be really welcome Blush

thanks,

Guy
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Mar 24, 2014, 19:50
Post: #2
RE: add an alpha map
I am not at all sure what the question is

This one has a 'cloud' with a copy of the cloud in a white (full opacity) layer mask
Layer menu -> Mask -> Add mask
screenshot http://i.imgur.com/Bk9367c.jpg

This is the same as Colors menu -> Color to Alpha with black as the colour.
screenshot http://i.imgur.com/sGJbUnP.jpg

If possible can you post an example.

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Mar 25, 2014, 12:32
Post: #3
RE: add an alpha map
Hi Rich,
thanks a lot for your answer! Idea
- with the 1st solution I could add the mask but didnt manage to paste the copy of the cloud in there, my mask stayed white..
- with the 2d solution, I managed to get the correct result.
How did you manage to paste the layer inside the mask?
thx,
Guy
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Mar 25, 2014, 13:49
Post: #4
Thumbs Up RE: add an alpha map
Hi Kevin,
wow, yes, it worked! thanks Smile
Guy
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Mar 25, 2014, 14:17
Post: #5
RE: add an alpha map
another way
Just looking at the layers dialog.

[Image: pz6f0r6.jpg]

1. If you click in the icon(s) you set the focus on either the image or the layermask The border changes colour to show which is active.
In 1. the image is active and you can copy it Edit -> copy or just a ctrl-c is the shortcut.

2. Clicking in the layer mask icon and the border changes colour, The layer mask is now active.

3. You can now paste Edit -> Paste or ctrl-v and you get a floating selection. Anchor the floating selection.

4. The layermask contains a copy of ...whatever you paste into it.

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Mar 25, 2014, 15:07
Post: #6
RE: add an alpha map
also worked, many thanks, I get a better understanding of the whole thing now Smile
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