Re: [Gimp-user] Seeking better "green screen" method

[Seth Burgess <seth burgess gmail com>]

You can try "Color to Alpha" using a background  color not found on the stamp, but you may end up needing to do back-filling under the stamp (draw on a layer underneath it) where it removed a portion, and it probably won't work that well for real-world images (slight variations aren't handled well by the algorithm).  You can also use a painting mode of Color to Alpha to only clean up artifacts a select-by-color and removal leaves, but that's more work.

The foreground extraction method is intended to do something similar to what you're wanting, but until the new one is ready (see http://www.youtube.com/watch?v=kkQ1r5g49d4) its only a binary selection so you'll not get nice removal of color components and you'll see bleed.

You might take a look at the Bluebox plug-in with GAP (you'll have to locate/install the GAP plugins for your platform); haven't used it personally but it seems like it has the right options.

Best of luck,

Seth Burgess

On Tue, Jan 17, 2012 at 2:29 PM, Chris Mohler <cr33dog gmail com> wrote:

On Tue, Jan 17, 2012 at 2:17 PM, Jay Smith <jay jaysmith com> wrote:
> Goal:
>
> To be able to select the background (for change to 100% black) without any
> "leakage" of the selection onto the stamp objects AND without ANY non-black
> color artifacts remaining after changing the selection to 100% black.

Question: have you tried scanning with a dark-as-possible background*
and then doing 'Colors-Levels' and dragging the right-hand slider over
until the background is "solid black"?

Also, the "halo" may be a result of the height of the objects/stamps -
have you tried adding weight on top of the objects to get them as flat
as possible?

Chris

* something black, with a non-reflective surface.

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