Stroke my alpha channel!

[Aharon Rabinowitz]

What I usually do is:

– duplicate the footage that has the alpha
– select the bottom of the 2 peices of dupolicated footage
– Add the following effects:
Image Control > Tint (Set black and white to the colors you want and then set it up to 100%)
Matte Tools > Simple Choker (Set the matt to a negative choke value, which spreads out the alpha channel – play with the numbers until you get what you need)

Alternatively, you could not do any of that, and select your layer and use the option called: Layer > Auto Trace. you could use the auto trace to either create a mask around your footage’s alpha channel – if it’s moving footage, like a movie, then the option above is better – or to create a new solid with the same exact alpha shape. Using that second method, you could play with the mask expansion to spread out the alpha.

Another option I just came up with is to use the Vegas Effect which can be used to simulate a stroke around an image countour. You have to set the effects hardness to 100% and set it’s start, mid, and end points to all have an opacity of 100%. Then just play with the width property for thhickness. Also, set it’s blend mode to under.

Personally i like the top method better (though i think it’s more processor intensive due to an extra piece of footage), but they all work, and you never know when one of these methods just won’t do…

—————————————-
Aharon Rabinowitz
aharon(AT)yahoo(DOT)com
http://www.allbetsareoff.com
—————————————-
Creative Cow Master Series DVD
particleIllusion Fusion Volume 1
available @ http://www.pIllusionFusion.com

[Mark Warner]

Marvellous!! I’ve found the simple choker version worked best, combining a little “Alpha Levels” tweak.

Many thanks.

[Mike Pindara]

If anyone is coming across this thread nowadays.

Layer > Layer Styles > stroke.
y viola

[Marc Hermitte]

Great. That was simple!
Also, the minimax works better than the Chocker for the previous technique.

[Radames Clemente]

Many thanks, really works! 👍

[Graham Quince]

When I saw the question at the top of this thread, I was all ready to jump in with layer styles, but then I saw the dates. 2005 ! The cow really is an institution.