NEW IN R21
Advanced Features ProRender ProRender Nodes The remaining nodes BlendMask
With this function you can define the opacity of the Foreground color compared to the Background color and also select the color components that should be taken into consideration.
This setting defines the opacity of the Foreground color and the degree to which it is mixed with the Background color.
Only the selected components of the input color will be taken into consideration by the node. The Alpha option expands the function of the node to the use of alpha channels.