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Bluescreen vs. Greenscreen


Stuart T

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Hi, I've read over a few debates about blue vs. green screen. Mostly, people say blue and green are about even. Each has it's disadvantages. I thought though that some sources leaned slightly towards blue. Because of the fact that it is further from skin tone than green. Also, blonde hair contains a fair amount of green. And blue spill is not as noticeable as green spill.

 

However, when ever I see a behind the scenes of a major motion picture, the actors seem to be against a green screen. Anyone know why that is? There's probably some use of blue screen in Hollywood, but I haven't seen it recently.

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Because of the fact that it is further from skin tone than green

 

That would be fine if you were only shooting naked people, but people are much more likely to be wearing blue in their clothing than green.

 

Green has a better luminance value than blue, so the background needn't be lit as much.

 

The Human eye is more sensitive to green than any other colour, and in many flavours of video green is sampled at twice the depth of the other colours.

 

As you pointed out, there are some advantages to using a blue screen, which is why it's still ocassionally used.

Lord of the Rings was shot with blue screens because of the use of green in the films palette.

It's just that in the majority of cases green is sufficient, if not more effecient to use than blue.

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Green has the most resolution when concerning film.

 

use whatever you want man, as long as its evenly lit ( cross light to avoid hotspots), and it's even color.

 

Hot pink would work, but I can give you a ton of reasons why not to use it.

 

Well there are technical issues when choosing Blue and Green for matting. When pulling mattes these days most effex houses prefer green because there is less noise in the green channel and you can pull a better matte (electronicaly) the blue channel tends to be rather noisy. Back when effects were composited on optical printers blue was prefferable since it is the farthest from skin tones and provided much better seperations. When transfering on either a scanner or a telecine the blue channel is less sensitive and has more noise than the green channel. With more noise it's much more difficult to pull a clean matte. If you know the post will be done electronicaly or you are shooting digitaly I would go with green unless you have green wardrobe or props. My general rule is to set the exposure for the foreground then light the green (evenly of course, within 2 tenths of a stop using a spot meter) to about 1/2 stop under the the exposure of the foreground. If you feel squemish about that then light it to exposure. This should get you a good matte in post.

Edited by rcfisher
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With my FX company, I prefer to let the production team decide so I can blame them later for making the wrong choice. :)

 

In actuality, given a choice and not knowing any details, I'd choose green. It works slightly better in most instances.

 

But first and foremost I'll ask what kinds of clothes are being worn, what kind of set pieces are being used. Those matter first.

 

BTW Khaki - lots of green in it usually.

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  • 2 weeks later...
Hi, I've read over a few debates about blue vs. green screen. Mostly, people say blue and green are about even. Each has it's disadvantages. I thought though that some sources leaned slightly towards blue. Because of the fact that it is further from skin tone than green. Also, blonde hair contains a fair amount of green. And blue spill is not as noticeable as green spill.

 

However, when ever I see a behind the scenes of a major motion picture, the actors seem to be against a green screen. Anyone know why that is? There's probably some use of blue screen in Hollywood, but I haven't seen it recently.

 

Blue was standard for travelling mattes until video took over from film.

The luminence signal is mostly green and relatively higher definition than the color difference signals, of which blue has the lowest definition.

 

Though some three-strip Technicolor travelling mattes used green. I think the original british patents, Tom Howard's, were for blue backing; TC Hollywood's were for green backing,

 

'The Conquest of Space', one of the last three-strip movies uses green backig for the live action and blue backink for the miniatures.

 

---LV

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