In this tutorial, we’ll learn about Keying, i.e., the keyer tool, mat tools, and screen presets.
What is Keying
Keying is the process of automatically removing part of a video to make a composite with another video or image. Usually, we’ll be removing color or tone. In the Effects panel, we can find a lot of effects for Keying. In the Keying folder, there is a subfolder called Matte Enhancements. Inside there, we can find a series of the impact that are meant to achieve a higher quality of output with Keying by making an extra adjustment to the key.
Also, we can find two combinations of effects in the Presets folder. So, in this video, we’ll go through each one of these effects and how they work. There are different possible scenarios where we might want to use Keying. We can record a video with a plain color background to composite with another background. Or we can use objects with these colors to make some special effects.
Use Different Key Effects
Sometimes, we might want to key out some tones of the regular video. Or maybe we want to add stock elements on top of our videos. For each case, we might use different Keying effects. For example, for a video made with a green or blue screen, we can use Color Difference Key. This is the main effect of removing colors from your image. It works with red, green, or blue.
For this video, we’ll select blue and adjust the minimum-maximum and gamma to approach the desired result. If we check the box for the View Matte, we can see the matte, which is a black and white image that represents the final value transparency. The white color will correspond to the visible pixels, and the black colors are transparent ones. The gray areas are semi-transparent. This feature can help us to be more accurate with our keying.
Chroma UV Blur
As this video is in the compressed format, the Key can usually present some pixilated or noisy edges. Chroma UV Blur will blur the Edges of these colors. If we apply this effect above the main Key effects, the edges of the key will be blurred and rounded.
If there is some unwanted fringe noise or stray pixels left in the Matte Edge, we can use the Matte Cleaner. One or combination of these options will improve the composite.
- Smooth will remove stray pixels by rounding the matte shapes. Use a small value to get a better and realistic result.
- Feather will soften the matte edge by blurring the edge of the matter shape. Again a small value will usually produce the best results.
- Choke will shrink the edge of the matte. A bit of choke can reduce unwanted fringing and noise, but be careful how much detail may be removed.
Most times, a colored background will reflect some of its colors onto the subject. Instead of keying out these colors, spill removal will help us remove those colors from the pixels. We’ll select the color of the background and adjust the strength to remove these blue reflections.
Hue & RGB Key
Later on, we only need to place the desired background and correct the colors to match the clips. If the color we want to remove is not red, blue, or green, we can also use the Hue & RGB key. This is an effect that’s useful to key out any other colors besides red, green, and blue. We can pick the color we want with the eye drop. Adjust the tolerance, soften the edges, and choose to key the color by the RGB values or by the Hue values. We can also run several instances of this effect to key out different tones of the same color or more than one color.
We can key up the brighter or darker areas of the clips using the Luminance Key effect. For example, we can remove the dark water in the shot to make some trippy composition.
Taking another example, we can key up the brighter areas in the sky of this shot to change it to a different sky.
Alpha Brightness & Contrast
For these kinds of compositions, we have some different effects of cleaning up the keying. Alpha Brightness & Contrast can help us to adjust the contrast and brightness of the Matte to adjust the keying of the composite.
Crush Blacks & White Alpha
Crush blacks and white alpha can help us to get rid of semi-transparent areas of the keying by turning them into rather fully transparent or fully opaque. The Erode White option will let us gradually expand the transparent area of the key to get rid of unwanted borders.
Invert Alpha will switch between the transparent and opaque areas. We can download elements or graphics to apply them to our clips. Usually, these videos will already have correct transparency, and we only need to put them on top of our videos. But that’s not always the case.
Sometimes, the clip can keep the remains of the original color of the background where it was created. For example, this graphic has been created on top of the black background, and we can see a little bit of black spilling on the Motion Blur. To get rid of this artifact, we can use the remove color matting effect.
In most cases, we’ll be taking out black spills, but if the effect was created on a background with another color, we could set the color in effect. For example, here’s the same graphic generated on top of an orange background. We’ll apply the Remove Color Matting effect and select the orange color to solve the problem.
Keying Black Background
If these videos don’t have transparency already included, we should key their background. Usually, these effects will have a black or green background. If it’s a green background, we can sue the color difference key to adjust it.
If it has a black background, we can use “Demult.” This is a fast effect to key out the black tones of the clip. In most cases, it will work perfectly. But if we don’t like the result, we can apply a Luminance Key effect and adjust the clip as we want.
If we still have some black borders, we can also apply the Remove Color Matting effect to get rid of them. If we are looking to key out a blue or green background, we can use one of the presets already offered by Filmora Pro.
Blue screen key and Green screen key, these effects will directly apply for effects in the correct order. So, we’ll only need to tweak them a little bit to get the results that we are looking for.
So, that’s how to work with keying. To learn more about editing in Filmora Pro, make sure to check out the other tutorials in the series.