Impromptu texture Mask/overlay

This will work with ether a mix color or mix shader node, You will need a background that is some solid color, Black,White or something that you can sift out with ether hsv or rgb would be best.

First I brought in a UV mapped dino man emission plane.



Here we are running the image though a color to rgb and a greater then math node (here is a point of play)


Here I had to swap the images on color 1 and color 2 to make things work.

Now to link this to someone that asked for it