Join Chris Meyer for an in-depth discussion in this video Compound effects, part of After Effects: Insight into Effects.
When we say that something is a compound effect, what we mean is that the effect is applied to one layer but is capable of looking at a second layer to determine how to process the layer it's applied to. All compound effects have several things in common, namely how they look at and how they deal with that second layer particularly if it's a different size then the layer it' s applied to. So let's go and see how that works. Here I have a piece of video and let's say I want to add an embossed bug down here in the lower right hand corner but there is a compound effect that does that called Texturize. So I am going to go ahead and grab my bug, drag it about where I wanted to be. Hit the Apostrophe key to see my safe areas, hit S to see the bug scale, bring it down and size a little bit and position it where I want it.
Now I want to apply Texturize to the video that's going to get the embossed effect. I will select it and choose Effect > Stylize > Texturize. You'll see that in Texturize there is something called the Texture layer. Whenever you see a pop-up for another layer, you've got a compound effect. I am going to go ahead and choose the bug and maybe you'll notice something is quite wrong. I don't have a bug down the lower right corner. I've got embossed @ symbols filling out my entire video. Well let's go back and have a closer look at the effect. There is a pop-up here called Texture Placement and you will see a similar pop-up in all compound effects.
It basically is asking you, how do you want me to treat that second layer? If that second layer is the same size as the first layer, everything lines up perfectly. But when it's not, After Effects needs to know what to do with it. Do you want me to tile it as we see going on here? Do you want me to just center it? Keeps the original size of the layer, not my scaled down size, but my original size and centers it inside my processed layer. Or do you want me to just take that layer and stretch the whole thing to fit? None of these are obviously the choice that I want.
Typically you are going to end up with Center Texture or some version of that. So I am going to back to that for now and show you the trick with compound effects. Take that second processing layer, position it, scale it, filter it, animate it, do whatever you need to do. Select it and this is very important, do Layer > Pre-compose. The shortcut is Command+Shift+C on Mac, Ctrl+Shift+C on Windows. When you select Pre-compose, give it a name that makes sense such as bug precomp, and say Move all attributes into the new composition. You want to remember in that new comp all the position, scale, animation, effects that you have done about layer. And just for fun I am going to open up the new composition. Click OK and you will see I have got a new comp, the same size of comp that I was just in, with my @ symbol down on this corner. So I will go back to my first comp.
Now when I select this layer and say let's choose the bug precomp, Center Texture. Turn-off the bug. You rarely want to see that second layer with compound effects. Now you see I have a nice embossed bug exactly where I want it to be down in the corner of my full frame layer. Now for this to work, the bug precomp needs to be the same size as the footage you've applied the effect to. Again, you need to do all of your work in the precomp, your sizing, any animation, any effects. Compound effects look at your second layers before any processing has been applied to them.
Now let me show another area where things can go wrong. Compound effects are looking at the black and white values of the second layer. Transparency, where my grid is in this case, clear alpha channel, is treated as black. Let's say that my bug was not white but happened to be black itself. I will turn-on the Transparency Grid so you see what's going on. Select my @ symbol and replace it with a black version of that @. I am going to hold down Option on Mac or Alt on Windows, drag it down and replace the layer. So there is my black bug surrounded by transparency.
I will go back to the first comp and I don't see any bug. The reason is since I have black pixels against alpha channel, which is treated as black, there is no difference in the pixels. So there is nothing for the compound effect to do. Therefore remember, you need high contrast. You need white, against either transparency or a black background and I am not talking about the comp's background color. That doesn't count. You can go ahead and create say a New > Solid. Make that Solid black in color, click OK, click OK, drag it behind your white layer and that will work as well.
And if necessary you could do the inverse. Let's go ahead and replace the bug with the black bug, there we go, take my Solid, open up its Settings, make it white in color. OK, OK. As long as you have black to white contrast the compound effect will now know what to do with those pixels. In this case, it's pushed into the layer instead of pushed out of the layer because the colors have been reversed. That's the main trick for dealing with compound effects. You have got two layers, the layer the effect's applied to and the second layer used to treat the first layer.
The two layers need to be the same size and that second layer needs to have high black to white contrast or white to alpha channel contrast in order for the effect to see it and treat the first layer.
After Effects gurus Chris and Trish Meyer share their real-world insight into how to get the most out of the effects that come bundled with this popular software. After Effects: Insight into Effects covers their favorite effects, hidden gems, optimal parameter ranges, "gotchas" to avoid, and alternative effects to consider. Among other tidbits, this course also contains "special topic" movies that pertain to more than one effect, demonstrate how to use After Effects more efficiently, and compare different effects to try in order to achieve a desired creative result. After Effects: Insight into Effects is recommended for all After Effects users, regardless of which version they use. This ongoing series that will be updated with new movies on a regular basis.
This course was recorded using After Effects CS4, but it contains many timeless concepts and effects. After Effects: Insight into Effects is recommended for all After Effects users, regardless of which version they use. This is an ongoing series that will be updated with new movies on a regular basis.