Using chroma key (green or blue screen) technology in your video projects is a fun and innovative way to add interest, professionalism and style to the design of your next video production. Â Generally, blue and green screen compositing is performed in post production which allows you to have total control over the look and feel of the final video production. You can also change the background or animation at any time during or after production (which helps if there are changes that need to be made later on). Â There are also a number of motion backgrounds andÂ virtual studioÂ backgrounds that you can choose from that allow you to transport your talent into a news type setting.
The mechanics of using a chroma key are easy: simply get a large green or blue background, video tape your subject in front of the chroma backdrop, then isolate and remove the color in your video editing software. Â Next, just replace the background with whatever you would like and render out the final combined footage. Â It is a fairly simple process, but there are some tips and techniques that can help you minimize frustration during production and post production.
Selecting your Chroma Background:
You can use nearly any color background for a chroma key as long as it does not show up in the foreground element/person you are trying to keep in the scene. Â Most chroma backgrounds are green or blue screens since these bright colors are easily seen by the camera and can be eliminated in the foreground subject matter. Â Green is a good choice for mostÂ beginnersÂ since the bright green hue is not present in most clothing or skin tones.
There are also multiple ways to create the solid green background. You can paint a large wall a bright chroma green (they even make chroma key paint specifically for this purpose), you can use a green piece of cloth from a fabric store, or you can purchase a muslin type professional green screen background from a video production store or online.
Whichever way you decide to go, you will want toÂ eliminateÂ wrinkles and variations of the main chroma color. Â Variations in the background color make it more difficult for the video editing software to cleanly key out the chroma color in the background.
Lighting your Green Screen Background:
Lighting is probably the most important aspect of your green screen video production. Â If you scene is well lit, you will have an easier time in post production removing the green screen in the background.
First off, setup your lights so that your background is evenly lit. You will want to avoid any hotspots orÂ gradationsÂ in your lighting. Â This can be achieved using a soft box or box type lights.
Next, light your talent. Â If you have the space, light your subject from a high angle using a spotlight or softbox. Â The high angle will helpÂ eliminateÂ hot spots Â on the chroma background and also will help keep shadows from the subject off the background (which can be hard to remove). You can also have a spotlight shinning onto the rear/back of the subject. Â This will help to create a clean, well lit edge of your subject which will also help in post production chroma key removal.
Setting the Scene
There are a few techniques that can be used in the setup of your scene that will help with your green screen video production. Â First, make sure your presenter/talent is at least 4 steps in front of your green screen background. Â This will help with two things. Â First, it will minimize shadows from the talent showing on the green screen background. Â Second, it will minimize spill which is when the chroma key background reflects onto the subject (reflecting on skin or light colored clothing). Since this reflection is the same color as the background you are trying to remove, it can confuse the video editing software and cause the subject to key out of the scene.
Because of the availability and quality, we recommend using the best HD camera you can find. Â Also, try to use a camera that allows for manual adjustments of ISO/Gain , white balance and shutter speed. Â ISO/Gain is a setting that changes the sensitivity of the sensor on your camera. Â A high ISO or Gain setting allows for low light shooting, but introduces grain and “noise” into the final video. Â We recommend manually setting your ISO or Gain to the lowest setting that you canÂ achieveÂ with the lighting in your scene.
We hope you have gained a few tips and techniques for your next video production. Â Green screen / Chroma key video production is an excellent way to improve the overall look and feel of your video production and it isn’t terribly difficult to do!