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 Post subject: alpha channel
PostPosted: 04 Sep 2009, 22:33 
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Joined: 12 Jun 2009, 10:56
Posts: 114
Hi all,

I would like to extract the alpha channel of a picture, and apply it to an other picture... Can you give me the tip?

extracting alpha seems prety simple : I take any comp node, and put the output in alpha mode. But I don't know the way to go to overide the alpha of the second picture.

Thanks


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 Post subject: Re: alpha channel
PostPosted: 04 Sep 2009, 23:24 
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Joined: 04 Jun 2009, 12:15
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Not sure (not an FXTree wizard), but it should be possible to limit the output (via the output options) of your second picture to RGB (instead of RGBA) and then use your extracted alpha as a matte... :-\


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 Post subject: Re: alpha channel
PostPosted: 05 Sep 2009, 13:01 
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Joined: 03 Jun 2009, 18:48
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Location: Germany/France
Hi,

it's easy and complicated at the same time, at least the solution I use:
Get a "Component Parser" and plug the picture that has the alpha that is to be replaced into input 1.
The picture with the alpha you want to use is plugged into input 2.
Then open the PPG of the "Component Parser" and enter
r[1](x,y) (for Red)
g[1](x,y) (for Green)
b[1](x,y) (for Blue)
a[2](x,y) (for Alpha)

Finished #:-s :D


Attachments:
ComponentParser.jpg
ComponentParser.jpg [ 76.1 KiB | Viewed 954 times ]

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 Post subject: Re: alpha channel
PostPosted: 05 Sep 2009, 15:52 
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Joined: 12 Jun 2009, 10:56
Posts: 114
Thank you very much for the tip. I just discovered a node wich can do the job easier : color adjust--> cutout (rgb+alpha)

With this one, you just have to plug your two pictures in the inputs....and that's all.


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 Post subject: Re: alpha channel
PostPosted: 05 Sep 2009, 16:19 
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Joined: 03 Jun 2009, 18:48
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Okay, that definitely sounds easier and quicker.

Sorry I had only the :-B solution to offer ;)

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