Chroma Key Your Way to a Green Screen Dream
You just need a little green to turn your video dreams into reality. Photo by Joel Fernando/Wired.com
This is a crash course into the process of shooting video in your very own blue- or green-screen studio space. Chroma keying is a visual effects technique that will allow you to change the scenery behind any actor on the cheap. In just a few minutes, you’ll be able to start shooting all the keyed-out footage that your wild imagination can muster.
You really don’t need much to start experimenting. I recommend that you don’t spend too much money as you get started. Keep it simple.
This how-to was written by Joel Fernando, a Brooklyn-based video scientist specializing in ghetto conundrums.
- 1 Materials
- 2 Prepping The Scene
- 3 Light the Blue Screen Independently of the Subject
- 4 Shadows Are Your Worst Nightmare
- 5 While Filming
- 6 Post-Production
- Blue/green fabric 8 x 10 feet minimum, a green/blue paper seamless roll from a video/photography store, or a bright blue/green wall
- Lights (clamp lights, 500-watt work lights, or your mom’s living room lamps)
- Gaff tape, duct tape or any type of tape that is strong enough to hold your pants up
Prepping The Scene
First you need a wrinkle-free fabric or roll of paper to use as a seamless backdrop. I use a $25 13- by 16-foot piece of fabric that I found on clearance at a fabric store.
Hang the screen in any wide open space — your garage or living room will work, but you’ll want at least an 8-foot-wide wall with at least 8 or 9 feet of vertical space where you can be positioned 10 to 15 feet away from to set up your camera. You want the fabric to lie on the floor with a curve.
Set up your camera on a tripod and determine the distance that the camera needs to be placed away from the subject depending on what lenses you are using. You want to make sure that the subject is a good 5 to 7 feet in front of the blue screen; this will prevent shadows from being projected by the subject onto the screen behind them.
If you have some money to drop, buy or rent a light package, but if you are going guerilla, you can use high-wattage lamps and any other lights that you have around the house. The goal here is to get the backdrop lit evenly. The best bang for your buck is to buy three or four 500-watt tripod-style work lights from the hardware store for about $35 a piece.
Light the Blue Screen Independently of the Subject
When lighting your “studio” set up, you’ll want to light the green screen first, then you can start lighting the subject. The main goal with a green screen is to maintain even lighting over the whole screen with no wrinkles or shadows that can cause variations in the hue of the screen. You can keep it evenly lit by diffusing the lights with wax paper and making sure they are at least 5 feet away from the screen to spread the light.
Shadows Are Your Worst Nightmare
Be aware that shadows from your actor’s movements or overexposed light spots on the blue screen will make the final product have a grainy artifact pixelation that glitches in and out in a sick way. Maybe you like that….
Now just place two lights on either side of the subject and play with the placement of the lights to tweak your style of lighting on your subject. Imagine the lighting of the scene that you are going to be creating for them in post-production.
A full setup, complete with tape, rigging, and lighting. Photo by Joel Fernando/Wired.com
Once you have your backdrop, lights, and camera setup, you are ready to shoot. If you are directing your subject in a small space, make sure that their body parts don’t move outside of the framing of the screen or they’ll be cut out of the shot. Shoot that shit, fool.
Once you are done shooting, all you have to do now is transfer all that footage onto your computer and use the keying filters to get rid of the green. I prefer Adobe After Effects with the Keylight 1.2 filter, a super powerful plug-in. Also, Final Cut Pro and Adobe Premiere have chroma keying filters that work really well. Newer editing programs have made keying pretty simple and effective. At this point it is really up to your imagination how far you want to go with effects and layering. Now you can layer all of that green screen footage of your subject on the timeline and psych all of your friends out.
Check out the video tutorial from Andrew Kramer of Video Copilot for post-production keying tips.