Just saw some behind the scenes footage of how CGI is done in movies like planet of the apes (actors in spandex suits & other little technology on the suits— presumably to identify spots with joints/limbs?) and in this specific case, the actors were wearing deep blue spandex suits.
I imagine this particular color selection had to do with shooting the scene in a forest— green suits would be more difficult to distinguish against a background with green foliage— but are there any other variables that are considered? I was just wondering why they would choose blue over, say, hot pink— I imagine some of the plants might have blue undertones and I would think that hot pink would also stand out and make it easier to add CGI. Are there any colors that are off limits, or don’t do the job as well (obviously dark/non-neon colors would be difficult to work with, but what about highlighter yellow or tangerine, or bright magenta?)?
Additionally any fun facts/video resources about film production would be cool & much appreciated! I just learned about the “pink haze” in copies of sailor moon apparently resulting from the degradation of the cyan & yellow inks and I find that super interesting, so I’d love any filmmaking facts along those lines. Thanks in advance!
In: Technology
green and blue area great because outside of makeup you wont find a skin tone that comes close to those colors………. you can use any solid color you wanted, like hot pink; so long as it isnt also in any scenery or prop
besides green being bad for forrests; and other nature scenes….green is much brighter in digital film/software making it easier for CGI teams to do their work adding to the film
It’s for a process called Chroma Key, where objects of a certain color are used to mask out elements that will be replaced in post-production. [Here’s a good primer](https://www.masterclass.com/articles/chroma-key-guide) on how Chroma Key works.
Chroma key compositing is a visual effects technique that involves using green screen technology, including chroma key software, to manipulate an image captured with a camera. By automatically selecting a specific color in post-production, video editors can remove the background from the image or an object within a scene that is that color. Substitute backgrounds can place actors in a new setting, and background videos might feature interactive animations. Object substitutions can allow CGI animators to replace live-action actors with computer generated enhancements or animated characters. Colors used for Chroma Key objects and backgrounds are usually certain shades of blue or green that are easily isolated by post production software and optical techniques.
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Green is usually the go-to because of three main reasons: 1 – it reflects the most light / is the easiest to light. 2 – it’s not near skintones in value/colour. 3 – most digital cinema cameras use a ‘bayer pattern’ sensor, which means that they have twice the detail when capturing green information than they do versus the red and blue primary colours. (this helps to pull a sharper ‘key’ to make the job of removing it easier)
We usually switch to blue when there is alot of green in the rest of the set. Red is avoided due to the fact that it’s close to skin tones. You _could_ use other colours, but generally it makes the key more muddy (cameras only have red, green, and blue photosensitive channels, so other colours will be a mix of those channels).
Like others have said, chroma keying will usually be the answer to the color chosen for body suits. However you mentioned POTA specifically. In those movies they use a suit that has a tracking pattern on the fabric. this is used to track the motion of the body and limbs to be retargeted to the digital character. Those are not ‘keyed’ (chroma keyed) out. the actors are digitally painted out of the frame. After the actor’s motion is retargeted to the digital character, the digital character is then composited on top of the painted background.
Depending on how close the foreground and background objects are (or objects to be matted out versus objects to retain), a consideration can also be scattering/diffuse reflection of the matte colour onto other objects close by (which the viewer will then notice as an unnatural colour tint). That’s less of a problem with dark blue, but can be an issue with green, and other hypothetical bright/strong colours.
Yellow would be too close to white/skin tones.
A couple of decades ago, for their studio news, the BBC pioneered using a retroreflective cloth matte (which looks like a silky grey most of the time) but if you then put a small coloured LED ring-light around the camera lens, the retroreflective cloth lights up brightly in the colour just from that particular angle of the camera. I guess the LED ring-lamp lets you swap between blue and green at the flick of a switch (to avoid particular colours on clothes), but also because you don’t have a large area of coloured cloth it avoids the colour-casts (and simplifies the complication of evenly illuminating a traditional coloured-matte background).
[https://www.bbc.co.uk/programmes/p005nby0](https://www.bbc.co.uk/programmes/p005nby0)
Or a newer youtube video [https://www.youtube.com/watch?v=2NYZxu4G3B4](https://www.youtube.com/watch?v=2NYZxu4G3B4)
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