Color Keying (also known as chroma key, green screen or blue screen) is a special effect/post-production technique used to composite two clips together. This technique allows you to remove a single color from your video. The color removed is usually the background of a video recorded in front of an evenly lit green or blue screen (like the weather forecaster at your local news station).
Color keying basics
To create the effect, you'll need a minimum of two clips and two layers (in the Timeline Editing Mode). One clip will serve as your background (a beach image, for example), and the other is a video clip that should be recorded in front of an evenly lit solid background (generally green or blue).
Creating the effect
Step 1- Lay the pieces
Drop the background on the Main Track then drag the "green screen" video in the track on top of the background.
Step 2- remove the color
To open the Color Keying controls double-click on the green screen video and switch to the Color Keying tab. Select the color that you want to remove (also known as the Key Color) with the help of the dropper tool. Try to get a sample in an area that is evenly lit while avoiding other colors. If you get too close to other colors, you might pick up more than one and the effect won't look as smooth.
Step 3- Defining the mask
WeVideo automatically removes the color and creates a mask that defines areas in your video that are transparent and opaque. To see the mask locate the "Mask" option and select it.
The mask is a black and white representation of the image; the black areas represent transparent sections of your video (that will be replaced with your background image). White areas represent opaque ones that will maintain the original video (your subject).
The goal when color keying is to refine the mask so that the color in question can be removed as best as you can. Use the sliders below to edit the mask and constantly switch between “Image” and “Mask” to understand how the different controls are affecting the mask.
- Gain - Controls how much of the color you want to remove. If you move it to the left, you'll start to see the green color in your image. If you move it too much to the right, you'll see your new background image appearing in places you do not want to. Play with this until your effect looks almost perfect and then use the rest of the sliders to refine the edges of the mask.
- Soften mask - Smooths the mask's edges to try to remove the color pixels in the difficult areas.
- Balance - Tries to balance the shadows that may be present in your key color areas so that you can remove them with more ease.
- Gamma - Adjusts the transition between the opaque and transparent areas in the mask to avoid color bleeding.
- Blur Edges - Blurs the whole mask, and it is useful in small quantities to remove jaggy pixels around edges.
- Defringe Mode - Helps reduce color bleeding at the edges of your mask. Use "lighten" or "darken" to match the edges of the mask with your new background image and play with the amount and the radius of this effect until you get it right.
Finishing the effect
Work with the sliders as best you can until you get a good mask. This will take some trial and error so be patient!
Make sure you check your mask at different moments of your video to ensure it looks good throughout the video. If you need to tweak it in only one section, split the clip by pressing S on your keyboard and the correct the new clip.
Note: The preview shows a compressed version of your video. The quality of the effect will be different once it is exported.
Color Keying Help
Having trouble viewing all the Color Keying controls? Use the resize tool to change the size of your preview window.
Want to revert the sliders to their original placement? Click on the revert arrow next to each one.
Want to revert your changes to the beginning? Click on the trash can on the top of the controls.
Made a mistake picking the color? Click on the trash can to revert and pick again.
When building your story remember to move both clips in the timeline, and make sure both are of equal length. You might need to zoom in to check this one.
Sometimes you might need to use tracks other than the main track for color keying (both for background and foreground). Since the main track is gapless, you might need to use a solid background as a spacer clip.