alpha channel

Discussions about FX-Tree and Compositing generally
Post Reply
julius
Posts: 248
Joined: 12 Jun 2009, 10:56

alpha channel

Post by julius » 04 Sep 2009, 22:33

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

User avatar
Hirazi Blue
Administrator
Posts: 5107
Joined: 04 Jun 2009, 12:15

Re: alpha channel

Post by Hirazi Blue » 04 Sep 2009, 23:24

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... :-\
Stay safe, sane & healthy!

User avatar
Mootzoid
Administrator
Posts: 243
Joined: 03 Jun 2009, 18:48
Location: Germany/France
Contact:

Re: alpha channel

Post by Mootzoid » 05 Sep 2009, 13:01

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 2886 times

julius
Posts: 248
Joined: 12 Jun 2009, 10:56

Re: alpha channel

Post by julius » 05 Sep 2009, 15:52

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.

User avatar
Mootzoid
Administrator
Posts: 243
Joined: 03 Jun 2009, 18:48
Location: Germany/France
Contact:

Re: alpha channel

Post by Mootzoid » 05 Sep 2009, 16:19

Okay, that definitely sounds easier and quicker.

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

Post Reply

Who is online

Users browsing this forum: No registered users and 19 guests