Green Screen with ScreenFlow Chroma Key

Lesson 5

What is meant by “green screen”?

A green screen special effect is a post production technique used in production of videos, newscasts and video games. Images are layered such that the subject in the top layer is in front of a green screen. The green colour is electronically removed from the top layer and the images from the second layer show up behind that image.

Green screen in Hollywood

green screen

  • Top picture from The Great Gatsby:
    • Green screen behind the actors and a prop
  • In editing room, all green in shade seen in picture is electronically removed
  • This reveals the next layer which is a period downtown scene
  • Video at the bottom of this page:
    • Examples of using green screens in Great Gatsby movie with Leonardo DiCaprio.

Cheap, homemade green screens

  • Green screens used in Hollywood movies:
    • Must have a uniform tone of green
    • They must have absolutely uniform lighting
    • They are expensive.
  • Video below:
    • Tells how to make inexpensive green screens out of green bristol board
    • Not have the professional quality of Hollywood
    • Bristol board is all you need for a course such as this one.


How to Create a Short Video with a Powerful Message

Inexpensive green bristol board

green screenGo to a dollar store and buy several sheets of green bristol board. Then go to a paint store and buy a roll of green masking tape.

Tape the sheets together on the wall that will be behind you as you are video taping yourself. Make a short video of yourself talking about a particular picture.

Save the video with a descriptive name.

Replace green background with picture

green screen

Using the ScreenFlow Chroma Key feature, replace the green screen with the picture you have chosen.

 

Let’s say that this ScreenFlow timeline represents first two layers of your particular timeline.

The top layer would be you in front of a green screen. The second layer would represent a ScreenFlow recording of the background picture. Click in the top row to select the video of you with a green screen in the background.

As described in the above video, select the Chroma Key colour choice rectangle. Click Video Filter > plus sign > Chroma Key > Add. That should give you the green color icon you see below.

Click on the color icon.  That will give you the Chroma Key colour choice rectangle. As you move your cursor about in the green area, the green screen will begin to disappear and reveal the picture that you have in the second layer. Keep moving your cursor around until the green screen is completely transparent.

Green screen use in The Great Gatsby

 

Lesson 5 homework

  1. Record yourself talking in front of a green screen you created with bristol board
    1. Name this video “Green Screen Sample” and save it.
  2. Using ScreenFlow, record a random YouTube action video.
  3. Drag the random action layer to below the green screen layer of your Green Screen Sample.
  4. Using Chroma Key, remove the green from the green screen layer.
  5. Save your new video as an MP4 file.

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