Mask to objects: Accept B&W contour images as input for cells.

Created by: tinevez

MASK_TO_CELL Returns the cells from a BW image with ridges.

This function takes as input an image that was generated e.g. with the morphological segmentation technique, where each object is white and separated from its neighbor by a black ridge. It then returns the a struct array, 1 element per object, containing the object boundary, the junction id this object touches and its center. As a second output it returns the junction graph.

This function only works for object in white with a ridge in black. The ridge must be connected using 8-connectivity.