What are Green Screen and Ultra Key effect in Premiere Pro

30 Jan 2020

4 Min Read

Why Green Screen?

From the dawn of cinema up until this day, the core idea behind creating film has almost always been telling a story and sometimes storytelling involves some scenes that are sort of impossible in different ways. The range will go from minor stuff like shooting a scene in exotic and unreachable locations, all the way to extremes like shooting scenes in space! That’s when Greenscreen comes to play! Let’s shoot the scene from the comfy greenness of our set and let the hassles be taken care of by the editing software!

Cool! Let’s do that! But how? How do greenscreens work? How should I set up? and before everything, why even green? Well, let’s answer that!

Movie Green Screen
Green Screen in Movies

Green Screen or Blue Screen?

Well, to first take care of the basics, Greenscreen was not always called that, cuz it used to be blue! Even today for the needed situation filmmakers and cinematographers still use blue screens. But the reason blue and green are the main keying colors is that, well human skin generally consists of many shades of red, and that can cause so many problems during the process of keying. Using Blue or Green is the easiest way to get around that issue and have a hassle-free post-production and editing experience. But when should we use green and when blue? Well, That one is a bit more complicated.

Alita Battle Angel Blue Screen
Alita Battle Angel (2019)
Avengers Endgame Green Screen
Avengers Endgame (2019)

Green Screen

Green is a much brighter color so it is much easier to light up and is more forgiving when it comes to wrinkles and shadows. Of course, if the background that you want to put in place of your greenscreen is a well-lit scene, like a sunny day, then for sure you can get away with using green, cuz the light of the scene will cover the edges. But if your scene is supposed to be dark, then you would be better off using a bluescreen.

Blue Screen

The benefit of a bluescreen is that blue color almost has no color spill so it can preserve the fine edges much better. But like everything in life, there is a catch. Bluescreens need so much more light on them to eliminate any sort of shadows on the screen. Bluescreens are also a bit harder to key out if the blue is not uniform.

So as you can see, choosing green or blue is completely based on the situation you wanna film in. Always picture the frame in your head and then decide on what color you want to use. The only thing you should take care of now and is common between both colors is how to set your set!

Setting Up A Green / Blue Screen Set

First, you gotta make sure the cloth is well ironed and wrinkle-free. Any type of shadow and inconsistency in the color will bring complications later on in the post. Next, you gotta both light the screen and the subject individually. Light, especially on the screen, should be soft, yet strong. It’s also good practice to have a backlight behind the subject, casting light on them so that their edges will be lit and mostly free of green light spill. This can really help out later on in the editing phase when you are trying to key out the greenscreen and you want to keep the edges nice and sharp. Also, make sure the subject is not casting shadows on the screen. Try to make them do different moves in order to make sure of that. It is best to always keep a distance from the screen to alleviate these sorts of issues.

Finally, it should go without saying, do not have anything on set that is green beside the greenscreen! Anything, no matter how small, can turn into a big distraction after keying the footage and that is a huge pain to fix in editing!

Green Screen Set
Green Screen Set
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Green Screen Set
Green Screen Set
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Green Screen Set
Green Screen Set
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Green Screen Set
Green Screen Set
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Editing in Adobe Premiere Pro

After importing both your footage into the premiere pro, you should stack them on top of each other in your sequence. First, the footage that is going to replace the green screen and then the main footage will go on top of it. Next, you should look for Ultra Key in your Effects panel and then drag and drop it onto your main footage. Then go to the Effects Control panel and down the list, you can find the Ultra Key.

First things first. You are going to use the color picker and choose the greenscreen to key it out, just like Magic! For almost all cases, this will work out just fine, but if you see some issues with the end result, you can always move and work with the sliders provided in the effects control. For example, Shadow and Pedestal are the first ones I will always tweak if I see an issue with my keyed footage.

Conclusion

OK, that’s about it! May your green screening adventures be fun, exciting and easily professional! Best of luck and Bye!

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