Hollywood studios have used green screen magic to
bring to life the unimaginable. Does that mean that
the technique is only reserved for the elite
cinematographer, or can anyone afford to float through
space or climb Mount Everest with the help of modern
technology?
While the process may informally be called “green screening” the proper term is “Chroma Key”.This is the technique of compositing two images or videos together through the removal of a specific hue or color. When “pulling a key,” you are separating your subject from their backdrop. In the editing process, you add a “plate,” or the background. Today, green is the go-to Chroma Key color this is because green is the color that is the least present in human skin tones. Another popular alternative is the lesser-known blue screen. However, it is harder to light since blue absorbs more light waves than green.
The two sample images above show the before and after of pulling a key where the green backdrop behind the speaker has been replaced with a brand-oriented step-and-repeat plate using the company’s logo. This example shows that chroma key screens aren’t just for Hollywood, but they can take corporate and industrial videos to the next level. They can even help improve your Zoom conference-call experience!
Whether you’re renting out a studio or you’re filming in your garage, the diagram above shows the basic set up that’ll work wherever you are. If you’re setting up in a studio, screens come in a roll of seamless fabric or paper, as well as walls painted with special Chroma Key paint (these are known as “cycloramas” or “cyc walls”). If you’re in an office or at home, Fabricas well as pop up/Collapsiblescreensare cost-effective and can adapt to your working environment. If you don’t have access to a Chroma Key screen, some frugal substitutes include an LCD TV screen, printer paper, or poster board. Since lighting can make or break a Chroma Key experience, ensure you have at least two lights, one on each side of the screen, to light it evenly. These light sources–whether they’re lamps or professional-grade studio lights –should be soft and diffused to prevent “spill” from adding a colored tint to your subject’s shadows and highlights. Bed sheets or softboxes can evenly diffuse any light.
Now that everything is set up, it’s time to film. Unless you are matching specific lighting on your plate, make sure your subject is lit evenly with soft, broad light, and is placed 5-10 feet from the Chroma Key. Remove any fly-away hairs and verify that your subject is not wearing anything that is the same color as the screen. Not doing so could lead to that part of your subject disappearing during the editing process. Some optional filming tips include shooting at a higher frame rate and dropping the ISO on your camera to prevent an extra spill. These technical adjustments are not mandatory, but then they can solve any finicky lighting issues on set.
Now that you’ve finished filming, you can begin the post-production process. Several of the most well-known video and special effects programs that can pull a key are Premiere Pro, After Effects, and Final Cut Pro. If you’re unable to splurge on these programs some other effective –and free –options like iMovie, Davinci Resolve, or OBS Studio will do a nice job, as willChromavid which is dedicated to the mobile-oriented filmmaker. Now that you know the tips to Chroma Keying properly, go out and create something amazing!
