Selectionist

Overview

Adobe After Effects is shipped with a number of extremely capable color keying plug-ins. To interact with my latest 3D shader minObjectID I required a simple chroma keyer that would make it quick and simple to select individual objects by their associated color ID for further processing as an alpha mask.

The ideal candiate should fulfill these basic requirements and not much more:

• Be as simple and efficient as possible
• Output a specific color and not whatever object was keyed
• The result should be invertible
• Be extremely precise with no room for tolerance
• Works in 8-, 16- and 32-bit color space

None of the included keyers met all of my criteria because they either didn’t work in floating-point mode or were simply overkill for my purposes.

I then remembered that I had once started to write a little chroma keying application a few years ago and so I decided to sift through my old backup drives in the hopes of finding this lost piece of code in order to rip out its guts and to form it into the ultimate Object ID selector for After Effects.
Fortunately, I ended up finding the project and here I am to write about my new plug-in, simply named Object ID Selector for now.

Features

This plug-in has quite few parameters, making it simple to setup. It’s in no way an all-purpose color keying solution, but for selecting IDs of objects I think this stripped down keyer is the ideal choice.

I have not yet considered solutions for the aliasing issues that might arise between overlapping objects but I hope to find a practical answer to at least mitigate the problem.