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Warp Pixels Around Alfa


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#1 marekje

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Posted 19 July 2010 - 05:25 PM

Hi,

Do know about some macro or easy work flow, how to warp pixels around alpha? Simply said I want to fill empty area by pixels around. See attached picture.

Thanks

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#2 ChadCapeland

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Posted 19 July 2010 - 05:29 PM

Hi,

Do know about some macro or easy work flow, how to warp pixels around alpha? Simply said I want to fill empty area by pixels around. See attached picture.

Thanks


Me, I would blur the alpha, use CFlt with a Sobel kernel to find the derivative, then add that to a X-Y gradient made from a CT where Red = X, and Green = Y. Then use that as the UV input for an offset or texture tool, or another CT.

- Chad

#3 Tilt

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Posted 20 July 2010 - 02:27 AM

Hi,

Do know about some macro or easy work flow, how to warp pixels around alpha? Simply said I want to fill empty area by pixels around. See attached picture.

Thanks


Chad's way sounds pretty cool :-) I've got to try that myself.

Another way that works quite well for cleaning dust or holes in a more uniform background (e.g. sky or greenscreen) is this: cut out the offending spot by painting/masking it with black in the RGB and alpha channels. Blur a bit, then unpremultiply (divide RGB by alpha in a channel boolean). The hole should now be filled with a solid color. Copy the new RGB channels to where the hole was in the original image.
You can repeat that several times with smaller blur radii instead of one iteration with a big blur to see if you get cleaner results.

#4 Gringo

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Posted 20 July 2010 - 02:53 AM

See also: http://vfxpedia.com/...s/BzPixelExtend

#5 trollkind

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Posted 20 July 2010 - 03:56 AM

That shot looks like it needs way more than a color fill though. More like tracking of the house and fence and filling in missing pieces with patterns already in the footage. Looks like a b*tch with the blurryness and tree branches inbetween the two layers and you can see from that freeze frame that there is a lot of shakycam going on.

#6 robocop

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Posted 20 July 2010 - 05:41 AM

in these case i usualy use my own technique...
Attached File  russiamanCompingTechnique.jpg   114.25KB   149 downloads



PS:
sorry for stupid gag :)


#7 trollkind

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Posted 20 July 2010 - 06:27 AM

:D
come on, no color/blur/grain matching of the band-aid and you call that compositing?! I hope it's at least tracked clean.

#8 jirka

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Posted 20 July 2010 - 08:16 AM

try attached (slow) macro. Similar to Chad's way...
hth
jirka

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#9 marekje

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Posted 20 July 2010 - 04:06 PM

Thanks guys for tricks. Gringos BzPixelExtend macro works best for me. During the weekend I try to create ChadCapeland idea, but it sounds to me a little complicated:)

#10 robocop

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Posted 21 July 2010 - 07:59 AM

wow! theo did cool comment on Gringo`s BzPixelExtend thread

http://www.pigsfly.c...indpost&p=20109




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