How to Create an Add Mask Using Adobe After Effects

If you are using the Chroma-Key effect in After Effects to make your video background transparent, and run into a problem with reflective objects disappearing, you can correct the problem by creating an Add Mask on a new layer of footage.

Instructions

Difficulty: Moderate

Things You’ll Need:

• Computer with Adobe After Effects
• Digitized video footage

1. Open After Effects and open your project.
2. Select the clip that you want to create the Add Mask on by clicking on the footage under “Layer Name” in the Timeline.
3. Press the “Control” key and the letter “D” at the same time to create a duplicate layer. Make sure you are working on the TOP layer of the two, by clicking on it.
4. In the tools menu select the Pen Tool.
5. In your composition window, carefully “draw” a circle or shape around the object or person that needs the Mask by left clicking on the footage. Make sure all of your dots are connected in a complete circle or shape.
6. Back in the Timeline, expand the options related to your clip by clicking on the little arrow to the left of the footage name. Then click the arrow next to “Mask” to expand it’s options, and click the arrow next to “Mask 1” (the mask you just created) to expand it’s options.
7. Click the little stopwatch next to “Mask Shape.” This adds a “Keyframe” to your footage, essentially saving your mask shape from frame to frame. In the pull down menu to the right of “Mask 1”, make sure that “Add” is selected. This tells the mask to remove everything in the frame that is outside the mask.
8. Scrub through your footage by dragging the “Time Indicator” in your Timeline through the footage. Make sure your person or object stays centered in your mask. If they or the object is in motion, it is likely they will not. You can adjust each dot of the mask individually by selecting it and dragging it to expand the mask.
9. Give the Mask Feather Option (in the Timeline) a value of approximately “3.” Save your work.