AFTER EFFECTS: Adding a lightwrap blur around keyed green screen footage

Adding a lightwrap blur around keyed green screen footage in After Effects:

Malcolm Finnie at DJCAD created this great workflow instruction for creating a lightwrap in After Effects.

Essentially this process takes a matte from the foreground image (in the case my green screen footage of Kerry) and creates a duplicated outline, slightly blurred, and reflecting the light levels of the background below (in this case sky).

The process:

You will need a foreground and background on separate layers.

Make sure each layer is pre-composed.

• Select your foreground layer and add Effects>Blur & Sharpen>Channel Blur
• Set Alpha Bluriness>1.0
• Under Edge Behaviour, tick Repeat Edge Pixels
• Right Click this layer and choose Pre-Compose...(choose Move All Attributes to the new composition)
• Name it Foreground Blurred

Duplicate the Background layer and call it Light Wrap

Place the Light Wrap layer on top of Foreground Blurred

• On Light Wrap choose Effects>Channel>Set Matte
• Set Take Matte from layer > Foreground Blurred
• Tick Invert Matte
• Choose Effects>Blur & Sharpen>Fast Blur (depending on your version of AE, search for this in the effects library - it may be listed as obsolete but can still be used)
• Set Blurriness > 30
• Tick Repeat Edge Pixels
• Set Transfer Mode > Add
• Adjust Opacity as necessary
• Duplicate Set Matte and move to the bottom of the list
• Untick Invert Matte

Image below showing the After Effects UI with the various light wrap instructions and effects highlighted in red.

Tip: Play the timeline to watch out for hair noise. I didn't notice hair noise in the static images, and then needed to go back and adjust the black and white clip planes in the Keylight 1.2 process and then pre-compose again, to get a clear image.