Chroma Keying Technique
Edited by Pat Bitton
January 21, 2021
Using a green screen can take your video project from good to great by precisely swapping the green screen with a digital backdrop of your choice, be it a serene beach or the depths of outer space. So what is a green screen? How does a green screen work?
What Is a Green Screen, and How Does It Work?
The green screen tool incorporates chroma key, a post-production technique that layers two images or video streams by turning the green color transparent. Here’s a quick rundown: videographers film with a smooth, monochrome green screen backdrop, then use chroma key in post to make the green color (chroma) transparent, and replace (key) it with the editor’s chosen background.
Why is green the best color? Because it gives the most contrast with natural human skin tones. In the final stage, the background color will be removed from the video. If the background color is similar to skin tone, people’s faces will disappear from the movie. You can also use a blue screen background, but it will require twice as much light and may cause problems when filming people with dark hair or clothing.
How to Make a DIY-Green Screen
A Chroma Key video is impossible to make without the most important “ingredient” – a green screen. The cheapest a professional green screen can be is $50 – a reasonable price for an advanced clip-maker, but a little too much for a first-timer. If you’re not ready to invest in professional equipment, simply make your own green screen. A DIY-green screen can be just as good as a professional one if made appropriately.
Here is how to make a green screen.
- Take a large sheet of non-glossy fabric, seamless paper, or other material, and paint it vivid green.
- When your homemade green screen is ready, either build support stands for it or just hang the backdrop on a wall in your room.
It’s as easy as that! The most important thing you should pay attention to is that the color must be uniform, no matter what you’re using: a poster board, a painted wall, or a sheet.
How to Use a Green Screen
Now that you have a green background for editing, it’s time to learn a few tricks. Chroma key green screen videos are quite challenging to shoot. Still, the preparatory steps we are to describe are vital and will affect post-production dramatically, so you’ll want to learn how to green screen properly. Here are some tips on how to use a green screen to create a stunning video.
Adjust the lighting
Lighting is integral to green screen footage, but it’s more than throwing some lights on the set and calling it a day. The Chroma Key technique works because the green screen is consistent and monotone. Adding too much direct light can disrupt the results.
So what’s the best way to light a green screen? With diffused, soft lights. This kind of lighting will eliminate hot spots and shadows, guaranteeing your final product looks smooth and natural – so much so that viewers believe you indeed filmed in outer space!
For lighting, try diffusion filters and stick to one consistent type of lamp (fluorescent or tungsten). When lighting from multiple angles, consider buying the same light twice or thrice instead of syncing all light sources. This will help further guarantee a cohesive green screen come editing time.
You’ll also want to light the green screen and your actors separately to avoid shadows. Study the background footage you’re swapping in to ensure the lighting on actors naturally mirrors the lighting you’d expect from that type of footage.
Focus on backdrop details
Setting up your green screen properly is vital. Just like you don’t want the light to disrupt the green monotone, you need to make sure the screen itself is smooth, consistent, and de-wrinkled. Creases or wrinkles can alter the actual color, so it’s best to make sure you invest in smooth, industrial standard green screens for utmost precision. Clamping the green screen in place is also a handy way to keep the backdrop tight and smooth throughout the shoot.
A few other things to keep in mind when using a green screen: your actors should avoid wearing green clothing. Anything that’s green in the scene will be removed when using Chroma Key, so opt for different colors unless you’re trying to go for this effect (e.g., for the effect of a head bobbing through the ocean, your subject would want to wear a green turtleneck, pants, gloves, and socks. You could also use a blue screen instead of green, but green is the most popular choice among video producers.
Set up your camera
The green screen technique doesn’t actually involve your digital camera – you shoot with the green screen then key it out in post-production – but that doesn’t mean you should hit record and see what happens. Here are a few filming strategies to keep in mind.
Exposure: Since you have lighting already, keep your ISO low to avoid noisy and overly grainy footage. Make sure the footage is bright enough to fit with the backdrop seamlessly. That’s where a quick test run can do wonders for the final look of your film.
Settings: Use an aperture of f/4 to f/5.6 to add a slight blur that smooths out your screen. Also, go for a shutter speed of about 1/80 or 1/100. This will minimize your motion blur.
Focal length: To ensure cohesiveness, match the focal length of the green screen footage and final background footage as possible. If you’re using stock footage, study the settings beforehand, then set up your green-screen scene to match it.
Quality: Film with the highest quality format your camera offers. It doesn’t matter if it’s a DSLR, smartphone, mirrorless camera, or camcorder; as long as you have at least 1080p, you’re all set – although 4K footage is even better.
Plan the general production setup
Keep your actors at least three to six feet from the green screen to avoid shadows. Also, think about the backdrop you’re swapping in. What makes sense for your subjects’ actions? Should they look one way versus another or walk in a particular direction (e.g., toward the mountain versus away from it?)
Also, don’t forget a sturdy tripod. With any film, you want the footage to be as steady and shake-free as possible – and that’s even more important when you’re fusing one video with another. Shaky subjects with a smooth and steady desert background will look glaringly off to the viewers.
Where to Download Green Screen Videos
If you’re looking for a ready-made video with a green screen, download it from one of the sources listed below.
One of the most popular sources of royalty-free green screen videos is Pixabay: more than three hundred videos and still pictures can be found there.Visit the Pixabay website
You can also find excellent green screen effects for free on Pexels: this website stocks about a thousand royalty-free green screen clips that anyone can download.Visit the Pexels website
Finally, you can download green screen stock footage for free from Videezy, another multimedia file source.Visit the Videezy website
Now you know where you can find green screen videos, but what about the backgrounds? You can either record videos yourself or download ready-made ones from a stock video website. Storyblocks is one such source. It’s an online video library with lots of stunning and funny backgrounds and animations in HD quality.
If you need still images for your video, Storyblocks Image Library is one of the best options – you’ll find awesome digital photos and clip art in high resolution.
How to Edit a Green Screen Video with Movavi
The right green screen software will make Chroma Keying both effective and seamless. Try Movavi Video Editor Plus to create stunning clips.
Step 1. Install Movavi Video Editor Plus
Download and install Movavi Video Editor Plus on your PC or Mac. After the installation is complete, launch the program.
Step 2. Import Your Media Files to the Program
Remember that in a Chroma Key video, one element is used as a background and the other – foreground. It can be two videos or a video and a picture. The foreground must be green screen footage. Now add the files that you want to combine using the Chroma Key technique. Click Add Files on the File import tab and select the appropriate items in the window that appears. Click Open to add the files to the program’s Media Bin.
Step 3. Edit Your Footage Using the Green Screen Video Effect
Drag both items from the Media Bin onto the Video Track. Then select the video you’re going to use as the foreground and drag it up. When you do, an Overlay Track will appear.
In the More Tools menu, select the Chroma Key tab. Click anywhere on the background of the video in the preview screen using the color picker tool – this will make the selected color transparent. Adjust the Tolerance, Noise, Edges, and Opacity parameters as you wish and click Apply. The background will automatically change to the one you’ve chosen.
Step 4. Save Your Chroma Key Video
When you are happy with the result, click the Export button. In the window that appears, enter the title, select the appropriate video format, quality, and destination folder. When everything is set, click Start.
This is how to edit a green screen video with the Movavi software. It also offers impressive effects such as Slow Motion, stylization, and everything you might need for a Hollywood-like movie!
Frequently Asked Questions
What software do you need to use a green screen?
Many video-editing programs support the Chroma Key (green screen) effect. Movavi Video Editor Plus is one such program. Easily change the background of your video to anything you like!
How do you put a background on a green screen?
If you have a video with a green screen on your PC or Mac, you can change the background of your footage to pretty much anything. All you need is a suitable program that supports Chroma Key. We suggest you try Movavi Video Editor Plus.
This is how to put a background on a green screen video.
- Install and launch the Movavi software.
- Import your media files to the program.
- Put the foreground video on an overlay track.
- Apply the Chroma Key effect.
- Export the video.
How do you edit a green screen video?
To edit green screen clips, you’ll need video-editing software that supports the Chroma Key technique. Try Movavi Video Editor Plus to create incredible clips!
* The free version of Movavi Video Editor Plus has the following restrictions: 7-day trial period, watermark on the output videos, and, if you’re saving a project as an audio file, an ability to save only half the audio length. Learn more
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