This goes through the various workflows of using a region of interest when masking. The “Region of Interest” refers to the area of a matte or alpha when it’s been combined with a mask or multiple masks. You’re basically adding to or removing from an existing matte or alpha. A typical use case is when you have created a matte or alpha, like a key for instance, and you want to isolate portions of the matte or alpha with a mask. We’ll cover the various techniques covered in the Classic Gmask node, Gmask Tracer Node and Action.