The Ghost in the mirror effect: how it’s done.

This little effect is one of the simplest you can do with Adobe After Effects or similar video compositing software. These days even editing apps like Premiere and FCP have the tools to do it but we’re using After Effects because we’re used to it.  There’s a step by step guide below but firstly, here’s the film:

To do it for yourself, first film the action on one side of the mirror and then without moving the camera or changing the lighting shoot the action on the other side. We’ll call these two shots the ‘Mirror  shot’ (for what you see in the mirror) and the ‘Action shot’ (for the live actor standing in front of the mirror)

Drag the Mirror shot into the composition window and use the pen tool to make a mask around the mirror. This is to indicate what part you’ll be cutting out:

When you have done the mask it should look something like this:

If you look in the Mirror shot in the timeline you’ll see your new mask (by default it will be called Mask 1). In order to make an invisible join between the Mirror and Action shots, feather the mask.

This makes the mask  boundary fuzzy, so when applied to the mask, it makes the layer look like this:

Then drop your Action shot into the composition window:

and simply plonk your feathered, masked Mirror shot on top. If you haven’t been moving your camera around between shooting these two parts it should fit snugly, like so:

One last note: remember to move the two layers so that the action in the Mirror and Action shots syncs as closely as possible. Some people have done this by starting off using just the action shot and its own reflection but this often leads to a jump cut when they cut to the mirror shot. If you’ve got the patience and a good actor who can replicate the same moves exactly you can get it looking pretty good. After all, it’s the sudden unsynching of action that results in the scary quality of this technique.

Try it yourself!  Scary or not, it’s a good exercise to help you get the hang of After Effects, masks and layering of video layers.