If you have ever watched a movie and wondered how they got the actors to appear in such fantastic and otherworldly environments? Or how they put them in a dangerous situation?
They can’t always be real places or created sets, can they? They most likely used VFX technology.
What would you say is the most recognizable VFX technique of course Chroma key (green-screen or blue screen) to begin with just in case you didn’t know Chroma key (green and blue screens) are used in production to be able to quickly cut out a subject from their background and compose them on top of something else?
This screen is usually blue or green, so the chroma key is often referred to as the ‘blue screen’ or ‘green screen’ effect. Chroma key includes images of artists and objects in front of a flat screen of the same color. This allows us to put real people into unreal environments to understand why this technique works.
But have you ever thought about why only Blue and Green colored screen is used?
The answer is because it is not a natural human skin or hair color, so it is easy for the editing team to edit the screen out of the footage and no part of the actor’s body or hair, or clothes will be removed at the time of editing process. And if any part of their costume is green, the screen will usually be blue instead and vice versa.
Now well let’s use the help of our coloring human skin tones naturally does not contain any green or blue colors in the skin tones live in this part of the colorway greens and blues live on the opposite side of the wheel. So, when we’re excluding them from the shot, we’re not affecting skin tones theory sounds awesome.
But we wish it was that simple on the practice though so why choose one over the other this time let’s check the color spectrum char the luminosity of green color is much stronger than any other color digital camera record green much brighter and cleaner. One of the main challenges with this technique is to light your background as flat as possible to avoid any tonal variations of the color.
Green screen vs Blue screen
The main benefit of green screens is less complicated lighting rigs Green is quite forgiving if you don’t have a perfectly flat background.
But as Green is so powerful the light spill on your subjects is more pronounced it may result in difficulties during keying and color grading to avoid aggressive color spill you may want to put your subjects as far away from the background as possible.
The blue color is less powerful luminosity wise therefore produces almost no color spill which may help you with a more detailed key.
But it’s much harder to light blue screens you will need much more powerful light panels to get scream evenly lit less luminosity and fewer colors pill helps with things like hairs and subject edges which is important for the quality of your key.
So, which one to use?
Whether you should use a green or blue screen depends on what kind of shot you are trying to achieve considering all the stuff.
And as mentioned above the green is a cleaner color and doesn’t need as complex lighting setups but spills a lot of colors and may result in bright edges and different artifacts all this makes green perfect for shots featuring bright backgrounds they light scenes bright edges would be less noticeable and you don’t have to worry that much about the details,
If you would try to place the same subject into the dark scene you would have to spend significantly more time to make it look acceptable it doesn’t make green screen unusable for dark shots is just not the best choice blue screen is perfect for dark shots it doesn’t spill that much color on your subjects, therefore, you have darker edges
Use of Chroma:
This is where the changeability of the effect comes in.
And you can edit or change almost anything into the background like footage from other locations, artificial sets, paintings, or even close-up footage of miniature sets placed in the background to make it look like the actors are in a full-sized version of the model.
Or you can also create an environment entirely out of computer graphics!
It’s not like we can use chroma in movies or filmmaking only “NO”, some of these techniques are also used outside of filmmaking. You’ve probably seen the news on TV and have seen someone talking about the weather while a giant map behind them explains what they’re saying. That image was placed there using a chroma key effect.
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