I'm working on a procedural material and got stuck with the following issue. My material generates a high contrast grayscale mask which is used to blend layers. I need to break up the edges of this mask with noise. In order to do that I gotta have some edge detect node setup. In Substance Designer there's is a special Edge Detect node for this which is based on blurring the input texture. In UE4 this can be done by "If" node and other methods. However, in Blender, there is no blur node or logic operators. The best I could do is the example below. It is not good enough, because the outline is too narrow and there is no control over its width. I will be grateful for any ideas on a better node setup. Examples illustrated below.
Desired effect from Substance Designer
Blender - Original Generated Mask Texture
Blender - Lousy Edge Detect Setup