CC detach, filtering

1. dealing with remaining CC after noise removal
1. do we re-index the obj so that the indices are an array of continuous numbers?
2. this means to re-index each pixel in the matrix, which requires time
3. we can use a dict to record the remaining indices in the CC map, which takes space of only 10- elems
4. go with dict !!!!
2. Matlab boundary detection
1. [B,L,N,A] = bwboundaries(BW);
2. % B = {obj, holes}
3. N = n_obj
4. A = [boundaries, r vs. c =  enclosing(i_obj_in_B) vs. enclosed(i_hole_in_B)]