Turns a base texture into black and white using a threshold.
With a greyscale texture, mask part of a mesh by adjusting a float parameter. This could be used to increase or decrease the amount of dirt in a mesh.
Base Image: Base texture to multiply.
Threshold: Greyscale color, with 0 as white and 1 as black.
Image: Base texture with the colors multiplyed, channel by channel, by a greyscale Color.