Tuesday, January 25, 2011

Toward robust chromatids labelling :

Holed, bended, round shaped chromosomes may lead to poor chromatids labelling with one pair of gray seeds. Here with several pairs of seeds, a much better labelling is reached:
Chromatids labelling after watershed
 The result depends on how the seeds were chosen. Four independent factors must be taken into account:
  • The pairs of seeds number:
    • One pair yields poor results as observed previously.
  • The orientation of the pair of seeds  relative to the chromosome
    • The axis of the pair of seeds, must be locally orthogonal to the axis of the chromosome.
  • For a given pair of seeds, the distance between the two discs.
  • The relative orientation of the pair of seeds
    • The pair of seeds must have the same orientation
The seeds used to get the result were choosen by hand:
seeds and edge of binary chromosomes in false colors.

When the seeds don't have the same orientation, watershed yields an harlequin  pattern :
Harlequin pattern (black holes are due to the absence of seeds to label the background)