Key light after effects tutorial 2nd Edition


This Keylight after effects tutorial will help you achieve good key even from a poorly lit, unevenly green carelessly shot green screen footage. As always we have broken down the process into 10 easy steps to follow. Let’s start.

Step 1 Keylight after effects tutorial

Create a new composition (Ctrl+N) in after effects. Make sure to create the composition size identical to your green screen footage. Drag and drop green screen footage into this composition.

Step 2 Keylight after effects tutorial

In case of lighting rig showing up in the scene or any other unwanted stuff you desire to mask out, go ahead and draw the mask.


Step 3 Keylight after effects tutorial

Best green screen examples have vibrant green color without wrinkles and are evenly lit. Don’t worry if your footage lakes these qualities because in this step we will be correcting those errors. From Effects and Presets panel select “Selective Color” effect. Apply it on green screen footgae. Go to “Selective Color” interface and click on colors button to drop down the menu. Select greens. Bring cyan, yellow and black values to 100 and magenta to -100 (negative one hundred). These settings in “Selective Color” effect should make your green screen bright and even .Click on the selective color fx button to turn it off and on to compare with original to see the difference. Depending on your footage you may need to duplicate the effect to get the desired result.

Before Selective color effect


After Selective color effect
After Selective color effect


Step 4 Keylight after effects tutorial

Go to Effects and presets panel and select Keylight. Apply it on green screen footage. Use the eye dropper tool next to Screen color button and click on a pure green color from your footage.


Step 5 Keylight after effects tutorial

Change the view mode in Keylight from final result to Combined matte. The matte displays three colors, black (100% transparent), gray(semitransparent) and white(100% opaque). Now click on the small color preview box next to Screen Color button which displays selected color. This will open color swatch move the cursor slightly down and to the left press ok. This will desaturate the green color which helps in removing more shadows and wrinkle.


Step 6 Keylight after effects tutorial

In Keylight interface increase the screen gain this will remove more shadows. Do not raise screen gain value not over 115. Next decrease screen balance not more than 45 this will make the white area uniform. A good range for screen balance is between 40  to  60.

After changes in Screen gain values
After changes in Screen gain values


After changes in Screen balance values

Step 7 Keylight after effects tutorial

Increase Clip black values to make the background black (100%) transparent . Clip black values should not be increased over 15. Decrease Clip white values to remove gray color (semi transparent)from the white areas.Clip white values should not be decreased below 85.

After changes in Clip Black
After changes in Clip Black



After changes in Clip White
After changes in Clip White


Step 8 Keylight after effects tutorial

Change the view mode in Keylgiht from combined matte to final result. Press Ctrl+Y to create a new solid make it comp size and with bright red color. Place this solid below the green screen layer. Now you can evidently see errors if present. By now you should have a descent key.


Step 9 Keylight after effects tutorial

Change the view mode to combined matte again. Select the green screen layer and precompose it (Ctrl+Shift+C). Name it Background green. Choose move all attribute and check open new comp then click ok. Now you are in Background green composition create new Adjustment layer and change its blend mode to Darken. This blend mode affects only the darker areas in this case the black area. Rename the adjustment layer as Black mask.


Go to effects & presets select Threshold, apply it on the Black Mask layer. In threshold effect pane move the value down till the background is completely black leaving soft gray areas around edges. Create another Adjustment layer change its blend mode to Lighten. This blend mode affects only the Lighter areas in this case the white area. Rename the adjustment layer as White mask.


Go to effects &presets, select Threshold apply it on the White Mask layer. In threshold effect pane as just the value up or down to make the white areas white, leaving small amount of gray between the White and Black areas.

After black and white mask layers
After black and white mask layers


Create another adjustment layer name it mask feather and apply Gaussian blur of blurriness upto 3.

After Mask Feather layer
After Mask Feather layer


Step 10 Keylight after effects tutorial

Duplicate the green sceen layer.


Select from top to bottom, Mask feather layer White Mask layer, Black Mask layer and one of the green screen footge and precompose.


Move all attributes and uncheck open comp. Rename it as Matte.


Drag the duplicate green screen layer above the matte comp and delete all its effects.


Go to effects & presets search for Set matte and apply it this layer. In Set matte effect click on take matte from button and select the Matte comp. Change Use from matte to luminance.


After Set matte effect


Hide the Matte comp layer by clicking on the eyeball. Now we have keyed out the green screen without affecting the subject. To remove the green spill select the green screen footage layer and precompose this time select leave all attribute, check open new comp. Rename it as Despill.


In Despill comp duplicate the green sceen layer. Apply Keylight effect select a bright green color as screen color. In effects and presets panel search for channel combiner effect and apply it on the same layer. Make sure that Keylight effects is above and channel combiner effects is below. In channel combiner effect change From and set it to Straight to premultiplied. Check alpha.


Change the top layers blend mode to Color.


If everything is correct all your green should be now gray.


Click back to the main comp you should now have a key perfectly despilled and ready to use on background of your choice.

Final result
Background composited with a little color correction


Hope you find this advanced chroma keying tutorial helpful. See you next time with another exciting tutorial on Chroma keying.