Color Theory - Green Screen & Chroma Keying

In my Multimedia Systems Engineering course we have an assignment to implement a chroma key algorithm. Our problem was to implement a chroma keying program that was flexible enough to handle a wide variety of colors with gradient backgrounds, without per-input tuning.

I’m not thrilled about the amount of time I spent chasing bad solutions - including a large chunk of time trying to implement “High Quality Chroma Key” and others. There are many chroma key solutions that produce high quality results in YCrCb space but require hand-tuning; the constraints of this project eliminate these options as good candidates.

A simple hueristic performs best across these cases. Convert the RGB images into HSV space, and filter pixels out of the background that land within certain H, S, and V counts with some tuning.

There’s some trouble at the edges, but for the purpose of the assignment the results are good. I implemented a Gaussian blur filter to smooth out jaggedness a bit.