Overview

Chroma Key is an effect commonly used to remove solid color backgrounds from images or videos.

The effect generates a greyscale luma matte based on a specified color. This luma matte renders black for pixels matching the chosen color and white for non-matching pixels. The matte is then used as a luma mask on the layer, making the matching pixels transparent.

You can find Chroma Key in the Block Browser under the "Color" category. It's often used for removing green or blue screen backgrounds from images or footage.

Initial Setup

When you first add Chroma Key to your layer or project, you may not notice any changes. This is because your layer may not have the effect’s default color present.

To begin, set the color you’d like to remove from the layer. Use the eyedropper tool on the block to set the Chroma Selection property (explained below).

Controls

Chroma Selection

The first color input field determines the color to be removed (or set to black on the matte). You can use the eyedropper tool featured on the block to select a color from the layer itself, or if you have a specific color, you can enter a HEX value in the input field.

Threshold

Threshold controls the similarity threshold for pixels that will be made transparent. A value of 0 means only exact color matches will be made transparent.

Smoothing

Smoothing makes the matte edge more organic and similar to what your eye sees on an image. It makes pixels semi-transparent that are similar to the selected chroma. Higher smoothing values include more pixels in the matte, creating a softer edge. A value of 0 means no smoothing is applied.

Output

Output controls what the block renders. There are two options:

• Luma Matte: Renders the greyscale luma matte generated by the block. Use this setting to inspect the underlying matte or use the layer as a cross-layer luma mask.

• Final: Renders the layer with the matte applied as a mask on itself. Use this mode to immediately remove pixels without needing to create or manage cross-layer mask connections.