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# Using Garbage Masks in Batch and the Modular Keyer

Certain garbage mask features are supported only in the GMask node in Batch and the Modular Keyer.

You can use a parameter called Region of Interest (ROI) when drawing multiple garbage masks on a clip to remove the portion of the matte that falls outside of each mask while respecting the area defined by all masks.

ROI enables you to reveal multiple parts of the matte.

Image courtesy of The Post Group

You also have the option of using the Tracer with an advanced gradient. The Tracer is an additional softness tool you can use to pull a key from scratch. This allows you to key images with a lot of detail at the edges. It uses a system of localized keys, called pickers, which analyse the colour information both inside and outside the mask to derive a key for the mask edge. You can use both the Tracer and the advanced gradient within the same garbage mask.

The Tracer is particularly useful for keying challenges such as:

- Very fine, wispy talent edges (hair, fur, or lace) where a blue or green screen may show through.
- An object not shot on a blue or green screen.

Garbage mask with pickers sampling image for more advanced softness Image courtesy of Behavior Communications Inc. | Garbage mask with pickers applied to only select vertices, the remainder using an advanced gradient Image courtesy of Behavior Communications Inc.

The Stabilizer and pickers are not available when this type of input is attached to the node.