Digital Home Thoughts: Adobe After Effects 6.0 Standard Reviewed

Masks
Masks are used to either hide or make visible portions of one or more layers. AE makes it very easy to create masks of shapes of your choosing, using a combination of straight lines and Bezier curves. You can then adjust those mask shapes over time. As with other keyframe usage, AE interpolates the values between the keyframes, resulting in a mask morph from one keyframe to the next.

In addition to using the tools to draw out a mask, AE supports pasting a mask from Illustrator or Photoshop, converting a text layer, creating a mask from audio and creating a mask using Autotrace.

Autotrace is a new feature for AE 6. It allows you to select a channel from the image that you want to mask. This channel would typically be the alpha channel but you can also use red, green, blue or luminance. The tool then creates a series of masks either for the current frame or the defined workspace. This particular tool has been used in the next example, which can be seen in Figure 4 - click on the image to download the movie.

This project uses two movies of a rotating yellow car. One is a wireframe car and the second is the solid version. To begin with, autotrace has been used on the initial part of the movie to trace around the rotating car. A scribble effect has then been used within the mask to draw the lines across the body of the car.

The audiotrace effect has been used to create the spiky yellow lines coming out from the edge of the car. This is keyed to the music track and is handled automatically by AE. Like most effects, you have wide control over the parameters that you can keyframe so that you could, for example, change the colour of the bars over time or their length or ... you get the idea :lol:. A radial shadow has been used on the final rotating car to give the illusion of moving from a drawing, through to wireframe and then to solidity.


Figure 4: Autotrace and audio trace in action. Click on the image to play the Quicktime movie (13MB)

Effects
After Effects comes with an amazing library of effects, arranged into the following categories: 3D channel, adjust, audio, blur & channel, sharpen, distort, express controls, image control, keying, matte tools, noise & grain, paint, perspective, render, simulation, stylise, text, time, transition, video. Phew!

Recognising that trying to find the desired effect is difficult in a menu structure, even when categorised, AE now has an Effects and Presets tool window that allows you to start to type in the name and AE lists anything that contains what you have typed in so far. Figure 5 shows the effects that have "col" anywhere in their name.


Figure 5: Effects and presets

I've mentioned a few times how the various parameters of effects can be keyframed and this can be seen in Figure 6. A large proportion of the power and flexibility in AE comes from being able to set keyframes on parameters and adjust them over time. It is also possible to stack multiple effects onto a single layer and change the rendering order of those effects, thus resulting in different looks.


Figure 6: Effect controls

A particularly powerful feature in AE is the adjustment layer. This is a layer that contains effects and those effects are then applied to all layers beneath the adjustment layer. An example of how this can be used is to have an adjustment layer over the picture of a brick wall. The adjustment layer could then have a hue/saturation effect applied to it which then darkens & shifts the colour towards blue for all layers beneath it, i.e. the brick wall. Adding a circular mask to the adjustment layer allows you to "cut" a hole in the hue/saturation effect, resulting in what can look like a searchlight playing over the wall if you move the mask around over time. If the adjustment layer was sitting on top of more than one layer, e.g. you could have a video clip over the brick wall of people pretending to break out of prison, then the searchlight effect would get applied across all of those layers.