The 3D Channel Extract effect makes auxiliary channels visible as either grayscale or multichannel color images. You can then use the resulting layer as a control layer for other effects. For example, extract the depth information in a 3D channel image file and then use it as an influence map in the Particle Playground effect, or extract values from the unclamped RGB channel to produce a matte that generates glowing highlights.
Note: To display 3D channel values for a pixel in the Info panel, apply the 3D Channel Extract effect, choose the channel from the 3D Channel menu in the Effect Controls panel, and then click the pixel in the Composition panel or Layer panel using the Selection tool.