What is chroma key and how does it work?
Chroma key rests on a simple principle: choose a specific color and remove it from the image. Green is chosen because it differs most from human skin and most subjects, and digital cameras record the least noise in the green channel. The subject stands before a uniformly lit backdrop — even lighting is the key success factor, since any shadow or hotspot makes color removal hard. In editing, specialized software removes the green and substitutes the desired background. The real art is capturing fine edges like hair and semi-transparent objects and keeping the subject's light and color natural in the new environment — which only experience and care achieve.
