Function chroma_key_definition 

pub fn chroma_key_definition() -> EffectDef

Returns the data-only definition of the built-in chroma-key effect.

key_color is compared against straight sRGB-encoded color, as a color picker shows the screen. With distance_mode rgb, pixels within threshold are removed, a softness band is partly transparent and spill_suppression desaturates it; chroma compares only chroma, so the key survives shadows.