Go to Effect>Color Correction>Auto Color to auto-boost the color. If you scrub your Timeline now, the key is looking good, so let’s restore some color into the clip and give it some punch. This gives us a much better edge to the key-perfect for an image like this at this size. Go to Effect>Matte>Matte Choker, and in the ECP adjust Geometric Softness 1 to around 4 and Choke 1 to around 2 pixels (no more). This reveals that we have slightly jagged edges, but we can easily smooth them out. Turn the Transparency Grid off to return the white backdrop. Now switch View to Final Result, and the first part of the key is complete. Now choose Screen Matte in the View pop-up to see the actual matte, then adjust Screen Shrink/Grow to –0.2 to trim the edges of the alpha channel slightly. Drag the Clip White to get Marina as white as possible, leaving some green (around 80). Twirl down Screen Matte in the ECP, and drag the Clip Black until the gray area around Marina is black (around 48–50). To further illustrate this point, choose Status in the View pop-up menu in the ECP to view the simple transparency information. Then, click on the Toggle Transparency Grid icon at the bottom of the Composition window to view the alpha channel-certainly not great at this point.
In the Effect Controls panel (ECP), click the Eyedropper tool next to the Screen Colour swatch and click on a midrange green in the image. With the layer selected, go to Effect>Keying>Keylight to apply the effect. Simply double-click on the edge of the mask border to resize and move it accordingly-but keep it as tight as possible to the focus on the shot. In the case of people dancing, jumping, and moving, arms, hands, or feet can easily go outside the garbage matte later down the line without you realizing. Go back to the main Selection tool (V) and scrub the Current Time Indicator (CTI) in the Timeline to check that none of your subject gets cropped during playback. This is removing all the “garbage” we don’t need-hence the name Garbage Matte.
In the Tools panel, select the Rectangle tool (Q), then click-and-drag a rectangle around the subject to remove everything except our dancing Marina. Now, when keying a large area like this with a small subject area, it’s best to first remove as much of the background as you can so the keyer has less work to do. Select your Green_01 clip and drag it straight into the Timeline. Finally, go to Composition>Background Color, click the color swatch in the Background Color dialog, and choose white in the Color Picker. Set the duration to at least the length of your clip (2+ seconds), then click OK. So go to Composition>New Composition, and in the Composition Settings dialog, set the Width and Height to 960×540 (16:9) with a Pixel Aspect Ratio of Square Pixels (when working on keying, it’s easier to see clean edges and results when not viewing expanded rectangular pixels).
Let’s work at the size this was intended for-NTSC Widescreen. Click the Create a New Folder icon at the bottom of the Project panel, name the new folder, and drag your clips into it to store them.
One of these clips “Green_01.mov” is available (shortened) for you to download from the Layers website. Here, I’m importing three clips of our intern, Marina, shot in HD in the green screen studio.
Locate and select the green screen clip(s) you plan to use and click Open. Starting out in Adobe After Effects CS3 with a blank project, double-click in the Project panel to bring up the Import File dialog. Once you have your footage, After Effects has some wicked tools to key and extract-and when combined they can create some wonderful results. With the accessibility of green screen setups these days, it’s easier to get keyable footage than ever before-opening up creative options without set or color restrictions.