Extract Lab
The Extract Lab component extracts an L, a or b channel from the source image or color according to the CIE L*a*b color model. L stands for lightness, and a and b are chromaticity coordinates. The channels are extracted as grayscale images, where light areas correspond to higher channel values, and dark areas correspond to lower channel values. For more information on the CIELab color model, see this Wikipedia article on the L*a*b color model. Extract Lab is a map component, it can be located in the Channels category on the Components Bar.
Source: Map Input
Provides the source image or color from which the specified channel will be extracted.
Specifies a channel to extract: L, a, or b.
Inverts the extracted channel.