Apple Shake 4 - Manual (Page 976)

976 Chapter 32 The Cookbook
The script begins with a Color–Reorder that puts the alpha into the RGB channels. It
then Filter–Blurs it, inverts that, removes the alpha channel with a Color–SetAlpha set to
0, and then is added back onto the plate. The Color–MDiv is used because the IAdd
disrupts the premultiplication status. The Color–Gamma can be used to tune the
intensity of the flare. Finally, preMultiply is activated in the Layer–Over.