Spill Suppression controls help to clean up green screen keys around light colors, such as blonde hair:

Soften: Blurs the edge of the alpha channel matte.

Choke: Shrinks the size of the alpha channel matte.

Matte Cleanup controls help reduce the size or soften the edges of transparent areas: Pedestal: Filters out noise from the alpha channel and can improve the key when working with low light footage.Tolerance: Adjusts the range of colors selected.Shadow: Adjusts opacity of the dark areas of the source image.Highlight: Adjusts opacity of the light areas in the source image.100 is fully transparent, and 0 is fully opaque. Transparency: Adjusts transparency of the source image when keyed over a background.

Matte Generation controls help refine transparent areas: Custom: Manually adjust transparency controls.Relaxed: Contracts the pixel color range for reduced transparency.Aggressive: Expands the pixel color range for added transparency.Use the Setting menu to expand or contract the selected color range for transparency: Use the Output menu to view the Composite Image, the Alpha Channel, or the Color Channel for the applied Ultra Key effect. The Ultra Key effect can be used to set any color in an image to become transparent and offers additional controls to refine the result. If your composite image still has a green cast, in the Effect Controls panel switch the Ultra Key Setting menu to Aggressive, expanding the selected color range to eliminate more green pixels.Right away, you see the image from V1 where the green had been. Click the Key Color eyedropper, and then select the green color in the image displayed in the Program Monitor.With the green screen clip still selected in the Timeline, and the playhead over it, open the Effect Controls panel to adjust the Ultra Key effect settings.From the Effects panel, in the Keying category, drag the Ultra Key effect onto the green screen clip on V2.Edit a green screen clip onto V2 in the Timeline, above a clip on V1.Use the Ultra Key effect to make a green screen background transparent. That’s why a key is often called a “green screen” effect. Subjects are often filmed in front of a green screen to make it easier to select the background color and make it transparent. What you learned: Select pixels of a particular color range to define areas of an image that will be transparent or opaque

Adobe premiere pro green screen