The Subtract component calculates the channel-wise difference between the colors supplied by the Source A and Source B inputs. The alpha channel is not processed in a channel-wise manner – the resulting alpha channel is taken from the Source A input.
Subtract is a map component, it can be located in the RGB Math category on the Components Bar. This component can output HDR colors. Like other RGB Math components, this component processes its inputs on a channel-wise basis, treating RGB channel values as signed floating-point numbers. For more information, see How Math Components Work.
Source A and B: Map Inputs (HDR)
These inputs provide the two colors to subtract one from the other. Both these inputs can accept HDR colors.
