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sebastian___
sebastian___
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How to add alpha information across multiple effects ?

Jun 27, 2012 6:47 PM

I have a single adjustment layer with some effects (linear color key or third party plugins). Like this :

 

1. Effect generates transparency - leaves only the lighter colors

2. The second effect should key out all the colors except a certain green hue from the remaining colors

 

But it doesn't work. The second effect will sample from the complete image and will ignore the keying performed by the first effect.

I also tried to do this with 2 adjustment layers and also with pre-compose. But it's not working.

The only working solution would be to export on disk the image keyed out with the first effect, import and apply the second effect. But that is very primitive, I hope there is another way.

600 Views   6 Replies   Latest reply: sebastian___, Jul 9, 2012 11:37 AM
 
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  • Mylenium
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    1. Mylenium,
    Jun 27, 2012 10:56 PM   in reply to sebastian___
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    You need to structure your comps accordingly - create the key in a pre-comp, apply the others in the parent comp. And most keying effects don't deal with already existing Alpha, so you need to fill in the voids with a suitable color or, which might actually be smarter, combine your different keying pre-comps with matte modes, i.e. key out the BG and the other colors in separate comps, then subtract B from A in yet another comp.

     

    Mylenium

     
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  • sebastian___
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    2. sebastian___,
    Jul 9, 2012 3:17 AM   in reply to Mylenium
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    Thank you for answer. This is probably the explanation :

    "And most keying effects don't deal with already existing Alpha"

     

    And even if I would use a pre-comp, I still had the same problem. But I found a very simple fix. It seems that if I would use multiple keying effects, it matters the order of the effects.

     

    Just by simple dragging a key effect on top or bottom of my second key effect, the result will be suddenly correct.

     
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  • sebastian___
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    3. sebastian___,
    Jul 9, 2012 7:54 AM   in reply to sebastian___
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    It's still not clear. I made 2 pictures with a schematic representation. These are just examples. With the adjustment layer 2 - I get that picture with transparency and I would like to add that to adjustment layer 1 image. Basically the adjustment layer 1 should be the background.

     

    this is what I want :

    http://img442.imageshack.us/img442/7974/desiredresult.jpg

     

    and this is what I get :

     

    http://img32.imageshack.us/img32/6803/resultvn.jpg

     
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  • voxL
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    4. voxL,
    Jul 9, 2012 8:17 AM   in reply to sebastian___
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    Could you upload a simple example?

     
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  • Rick Gerard
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    5. Rick Gerard,
    Jul 9, 2012 11:26 AM   in reply to voxL
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    Your adjustment layers need to be in pre-comps. An adjustment layer effects all layers below it.

     

    Does that make sense?

     
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  • sebastian___
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    6. sebastian___,
    Jul 9, 2012 11:37 AM   in reply to Rick Gerard
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    Thank you for answers. I found again a workaround with trackMat.

    I was trying to avoid using too many pre-comps.

    Perhaps when Adobe will add a complete schematic view (with nodes) a la Combustion and Nuke - everything will be finally clear. Hopefully an implementation where the default classic work mode will coexist with the schematic view mode.

     
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