A set/groups of binary masks, such as the one shown in Figure , are being used to remove unwanted parts of the image residue, in addition to other alternations to the data - alternations that are intended to give models which can be presented for meaningful variation. Had a method for mask synthesis and data making been formally described, it would have been a lot easier.
Looking at the same type of transformation but combined (both thresholds and mask) from another angle, it looks something like the examples in Figure .