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AE FavoritesCreate a favorite unmult effect in AE halo effect created in my last exercise , you were probably equally disappointed when you tried to apply the effect over a colored backdrop. Quickly the effect went in the toilet for one simple reason the black portions of the effect do not key or at least not yet. In this After Effects exercise, well create our own Unmult effect and save it as a favorite.
If you are familiar with Knolls collection of great effects, you are sure to have used Unmult at some point in time. This effect essentially removes the dark (black) portions of an image and creates an alpha channel out of them. This is a great effect to use when you have a layer with lens flares as you can easily remove the layer color and the fringe black around the flare.
When Knoll effects were picked up by Pinnacle Systems, the effect was a freebie, and those that grabbed it then were hooked. Recently, when Pinnacle stopped marketing and selling their AE plug-ins, the Unmult effect sort of disappeared and became difficult to fine. Now that Red Giant Software has picked up the effects collections from Pinnacle, you can once again download Unmult for free.
Recently there has been a lot of discussion on the After Effects mailing list about Unmult, whether or not it should be a standard part of AE, and how you can take this effect with you as you move from one project to another. The idea for this solution goes to Brian Maffitt at Total training. Well modify his suggestions and get results that are so very close to Unmult, youll wonder why you searched the Net so frantically trying to find the freebie.
The Unmult Effect
Ill begin where the Let It Shine exercises ended with a great looking white halo. To the Noise layer, apply Effect>Channel>Set Channels to the bottom of the effect stack. This effect allows you to Set the channel of the current layer to a channel of a different layer.
If you leave the Source layers set to None it will use the current layer. All you need to do is change the Alpha to Luminance.
By using the Set Channels effect, you dont have to pre-comp the layer to get it to work with other effects.
Following the Set Channels effect, you need to apply Remove Color Matting from Effect>Channel>Remove Color Matting. This will remove the haloing or fringing that can occur. The result is that it restores a great deal of the detail in the Fractal Noise.
The end result is that your halo effect is now capable of being placed on any colored background and it (the background) will show through where appropriate.
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