comping alpha in pshop...

[rfellers]

Came across this article that may help people comp elements in photoshop...

http://www.digitalartform.com/archiv...iting_pre.html

Basically the method is...

Top layer - rendered object on black background (no transparency or alpha on this layer!). Set blending mode to linear dodge(add).
Middle layer - 'holdback matte' - solid black fill using alpha of top layer.
Bottom layer - your background plate.

No black/white/colored outline at the alpha edges - works great!

[Pictor2]

Great tip, thanks! Those nasty white edges have always bugged me, not anymore..

cheers

[RErender]

From the comments

archibald | October 25, 2005 2:58 PM | Reply
Am I wrong in that if one renders premultiplied on either a Black or White, then using photoshops':
LAYER > MATTING > REMOVE BLACK/WHITE MATTE
will do this same thing in one shot?
I've been doing this for 3 years with no issues.
Am I missing something?
Just curious
Great site btw!!

Joseph Francis | October 25, 2005 4:43 PM | Reply
Nope. You are right.

[dlparisi]

This doesn't seem to be working correctly for me. The edges still look a little wrong-it only works correctly if I'm in 32 bit mode. Also the "Remove black matte" looks slightly different too. Anyone else?

[themaxxer]

this also works with a *.tga 32bit with "premultiplied alpha" unchecked.

best regards
themaxxer

[voltron7]

thanks for the helpful link