How to take high quality chroma key in Adobe After Effects CS5 ? (Part 2-Creating a chroma key)

Chroma key is a technique that allows you to composite two images or layers together by removing a specific color from one layer to reveal the layer behind it.Most often you use chroma keying to separate  a blue or a green screen from a video and replace it with a different background.Chroma keying is often used on television in weather reporting and films where virtual backgrounds are used.

It is important to set up a blue or a green screen with even lighting and the avoidance of shadow,because it is best to have as narrow a color range as possible for chroma keying.The first step in creating a chroma key is to create a garbage matte.This tutorial will teach you to create a chroma key itself.

Steps To Create A Chroma Key

There are several methods to create a chroma key in after effects.The keylight plugin pre-installed in after effects will help you get the job done faster than any other.But we are going to learn a more advanced technique using the color range option.

1. Click on the green screen footage layer in the Timeline panel with the chroma key composition still active.
   
2. Select Effect > Keying > Color Range from the menu bar.
   
3. Select the first eye dropper tool  in the effects control panel next to the black and white thumbnail preview.
4. Click the green background in the Composition panel.This begins keying out the background.
   
5. Select the second Eyedropper tool with a plus sign next to it in the Effect controls panel.This tool is used to add colors to the color range that the effect removes.
6. Click the area in the composition that is still green.
   
7. Set the Fuzziness to 50 in the effect control panel to remove some of the green fringes around it.
   

The green screen is completely removed from the frame except the slight bluish border around the subject.You need to refine this matte to remove the border that you will learn in the next section.

Note: In a situation you over select a color you can exclude the color from the color range using the eyedropper with the minus sign.

Video Tutorial

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