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Chroma Key
Chroma keying (also called "green screen" or "blue screen") is a compositing effect where a range of colors is selected and made transparent.
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source(image) - image to be processed -
screen(color) - screen color. i.e., the color to remove- default: Red 66/255 Green 195/255 Blue 31/255
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weight(number) - how much of the screen color to remove from semi-transparent pixels- min: 0
- max: 1
- default: 1
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balance(number) - it's complicated. Play with it.- min: 0
- max: 1
- default: 1
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clipBlack(number) - The minimum resulting alpha value of keyed pixels- min: 0
- max: 1
- default: 0
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clipWhite(number) - The maximum resulting alpha value of keyed pixels- min: 0
- max: 1
- default: 1
Chroma keying is a complicated process that depends heavily on the quality of lighting in the shot. This algorithm seems to work pretty well with well-shot footage, even properly keying shadows and reflections. But don't expect it to work well with badly-lit webcam video. Keying is based on saturation, so it's best to make sure your screen color stands out. You may see some edge spill if you have a lot of motion blur or compression artifacts.
clipBlack should be less than clipWhite. Things get weird if they're reversed, so it's best to avoid it.
- Minor optimization
- Experiment with despill on adjacent, opaque pixels
By Brian Chirls
Released under MIT License along with Seriously.js