Why are movie scenes shot with green background?

Why are movie scenes shot with green background? - Aerial Photo of Mountain Surrounded by Fog

I remember reading that green colour makes the best contrast with colour of human skin so in post editing it is easier to remove it.

Is that the only reason why they use green backgrounds when filming movie scenes? I would think that different skin colour would contrast differently against green background, which would invalidate this theory.

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Best Answer

According to the Wikipedia entry for chroma key:

Green is currently used as a backdrop more than any other color because image sensors in digital video cameras are most sensitive to green, due to the bayer pattern allocating more pixels to the green channel, mimicking the human eye's increased sensitivity to green light. Therefore, the green camera channel contains the least "noise" and can produce the cleanest key/matte/mask. Additionally, less light is needed to illuminate green, again because of the higher sensitivity to green in image sensors. Bright green has also become favored since a blue background may match a subject's eye color or common items of clothing such as jeans.

So yes, part of it may be because it contrasts better with human skin and other natural tones given blue could end up being a bad choice for anyone with blue eyes, or certain types of clothing being present in the shot. Given it takes less light to illuminate as well, this likely allows green to be used with smaller, cheaper, and thus more portable and budget friendly lighting solutions, perfect for TV show production or even remote filming where carrying bulky lighting setups could add to the time and cost of a film.

However, blue exists because of certain coloring needs. Night shots, either filmed at night or to be keyed as night shots later, work better with a blue screen; conversely, daytime shots work better with green screens. Should any edges around the subject not be fully removed, blue is less noticeable in nighttime shots, where as green is less noticeable in daytime shots.

You also need to be careful with green, as it tends to spill out quite a bit when illuminated. Should your subject be too close to the screen, the light could spill over their edges, which will then be removed in post.

For good measure, and because I like his videos, here's Tom Scott to talk about the process before green and blue screening.




Pictures about "Why are movie scenes shot with green background?"

Why are movie scenes shot with green background? - Landscape Photography of Cliff With Sea of Clouds during Golden Hour
Why are movie scenes shot with green background? - Houses Near the Rice Wheat Field Under the Clear Blue Skies
Why are movie scenes shot with green background? - Foggy Mountains at Sunset



Why green background is used in film shooting?

Film-based compositing methods preferred blue screens, due to the availability of blue-sensitive films. Green screen works slightly better for video as there are more green-sensitive pixels in common camera designs than red or blue. And blue coloured clothes are harder to avoid than green ones.

Why is green used for special effects?

Green is used because it is far from skin color in the color spectrum. When the software intends to remove the green it will assign transparency to a certain range of color, if the actors are wearing colors that are too close to the greenscreen color, their clothes will disappear. At times blue is also used.



Top Amazing Work in movies (VFX) (CGI) before and after shot




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