How to do apply water segmentation technique locally on different labels of labelled matrix?

I have got the labelled matrix from the binary image and now I have to apply the watershed technique locally on individual label at a time and this can be accomplished by putting all the labels in a loop to separate all the objects.

My AIM: The basic principle consists of performing a series of iterations that enable the segmentation to become progressively more refined, while largely allowing for under-segmentation in each iteration. In this method the concept of labels is used, which is defined as a cloud of connected solid voxels in the binary image that is not in contact with any other solid voxels. Each iteration consists of two main operations: (a) identifying all the labels in the binary image, and (b) for each label, performing modified watershed segmentation accordingly.

I have modified the watershed segmentation but unable to process the segmentation iterativelly.

Example: (a) after first iteration

(b) after second iteration

Kong,D & Fonseca, J. (2018)