Keying Green Screen in After Effects

Applying the Keylight Effect

Place your footage in the timeline. Then go to the Effects & Presets panel and search for Keylight. Select Keylight 1.2 and drag it to your footage. Now select your footage and open the Effect Controls panel. You should now see Keylight listed along with it’s settings.

Using a Garbage Matte

Often times a green screen shot will not make use of the entire frame. Your shot will often have objects on the edge of the frame you want to remove such as lights or stands.To get rid of this, create a garbage matte around the subject. This is a mask that is big enough to contain our subject but small enough to remove parts of the shot you want to get rid of.

To create a garbage matte:

  • Select your footage then select the pen tool.
  • Next draw a rough mask around your subject while leaving enough room to contain any of their movement. This will mask out the extraneous parts of your shot.

Achieving a Basic Key

  • First, select the Eyedropper tool next to Screen Colour in the Keylight effects settings.
  • Move your mouse to the color you want to key out and click. Try to get as close to your subject as possible while still selecting the color and not the subject.
  • After clicking, you will see that the color is mostly removed, however, it is rare to get a perfect key without further tweaking.

Fine Tuning Your Key In Status View

The first step to improving your key is viewing it in a different way. To do this, choose the Status option under the View dropdown in the Keylight settings. This view exaggerates the key to show you what is being keyed out completely, partially, or not at all by using black, grey, and white respectively.

  • The next goal is to make as much of the background solid black, then make as much of the foreground solid white, while retaining a very small amount of gray around the edges.
  • To achieve this, expand the Screen Matte menu under Keylight settings. The top two options here, Clip Black and Clip White, are the most important.
  • Increase your Clip Black until the background becomes black. Next decrease your Clip White until your subject becomes almost entirely white. Again, try to keep a small amount of gray near the edges of your subject. You will also see some green. Anything that is green represents areas that Keylight will attempt to color correct to remove spill.
  • You can see the difference before and after by comparing the Final Result view to the Intermediate Result View. The Intermediate Result view does not show spill suppression or color correction by Keylight. We will come back to this later.

Fine Tuning Your Key In Screen Matte View

  • Next change you view to “Screen Matte”. This view is similar to the Status view but it does not exaggerate your key. Instead, it uses white and black to represent what is and what is not being keyed out.
  • Again, use the Clip Black and Clip White options to fine tune your key. Adjust the two options so there is no white noise in the area you want to key out.
  • Then try to remove black noise from the area you want to keep. Once you have created a clean key move on to the next step.


Removing Spill and Noise

  • Often times your subject will have a green tint when filmed on a greenscreen. Keylight will try to automatically get rid of the tint by color correcting it but this can lead to noise. Rather than using Keylight automatic color correction we will use two other effects.
  • First, set the view mode in Keylight to Intermediate Result. As mentioned earlier, this view shows you the result without Keylight spill or color correction.
  • Next, search for Key Cleaner in the Effects & Presets window. Drag and drop the effect onto your footage.
  • Then search for Advanced Spill Suppressor and drop this effect on your footage too. Generally the default settings will look pretty good but tweaking can help. You can try adjusting the Key Cleaner edge radius and strength.
  • You can also adjust the Advanced Spill Suppressor suppression level. After this your key is complete.
Was this article helpful?
0 out of 0 found this helpful
Have more questions? Submit a ticket