Using the Chroma key type

Use the Chroma key to select a color or a range of colors in the clip to be transparent. You can use this key when you have shot a scene against a screen that contains a range of one color, such as a shadowy blue screen. Select a key color by clicking the color swatch or by using the eyedropper to choose a color from the thumbnail beneath the color swatch; use the slider bars in the dialog box to adjust the color that you want to key out.

Adjust the following Chroma key settings as necessary:

Similarity Broadens or reduces the range of color that will be made transparent. Higher values increase the range.

Blend Blends the clip you are keying out with the underlying clip. Higher values blend more of the clip.

Threshold Controls the amount of shadows in the range of color you keyed out. Higher values retain more shadows.

Cutoff Darkens or lightens shadows. Drag to the right to darken shadows, but do not drag beyond the Threshold slider; doing so inverts gray and transparent pixels.

Smoothing Specifies the amount of anti-aliasing that Premiere applies to the boundary between transparent and opaque regions. Anti-aliasing blends pixels to produce softer, smoother edges. Choose None to produce sharp edges, with no anti-aliasing. This is useful when you want to preserve sharp lines, such as those in titles. Choose Low or High to produce different amounts of smoothing.

Superimposing and Compositing > Using keys to superimpose and create composites > Using the Chroma key type