Posts Tagged ‘color space’

Going Green

Thursday, July 16th, 2009

shoot_greenscreen2Many of our video projects are shot on location, but every so often we have an opportunity to so some green screen work for a client. Shooting a subject against a green screen will allow the video editor to remove the green background and replace it with another of his or her choosing. Green screens are used every day on the evening news when the weatherman delivers the forecast.

Working with a green screen can be tricky, because if not done correctly, you will have nightmares in post production as you try to key out the screen and insert your own background. My recommendation is to shoot some practice footage first before you start work with your client.  Here are a few things I’ve learned from my experiences:

  1. The green screen should have no wrinkles or folds. Any imperfections across the surface of the green screen will result in shadows and hard lines that will be difficult to key out in post.
  2. The green screen should be evenly lit. There should be no shadows and no fall off. The light should be soft and diffused. A light meter will help ensure accuracy.
  3. Create distance between the subject and the green screen. Any light reflecting off the green screen and onto the subject should be eliminated. If not, your subject’s edges will have a green glow when the screen is keyed out. Move your subject as far away from the screen as possible. Then use flags to block any reflected light coming from the screen.
  4. Shoot on a format with the highest-rated color space possible. MiniDV has a color space of 4:1:1. You can use it for green screen work, but it isn’t the best option. Just be aware that there will be some challenges in keying with MiniDV footage. The edges on your subject won’t be perfectly clean. However, if your video is intended only for the web, MiniDV will work for you. Consider this video we produced. It was shot on MiniDV and the client was satisfied with the green screen work. Formats like DVCPro and DVCProHD have a color space of 4:2:2, making them better for keying.

Learning the proper video production techniques takes practice. There’s always something new to learn and the more time you spend shooting and editing, the better your craft will be.

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