MorphologyOps.foreground_component() ignores connectivity parameter, always uses 1-connectivity

[herryliq]

Problem Description

The MorphologyOps class in 1 accepts a connectivity parameter during initialization, but the foreground_component() method 2 completely ignores this parameter and always uses scipy's default 1-connectivity (4-connectivity for 2D, 6-connectivity for 3D).

Current Behavior

def foreground_component(self):
    return ndimage.label(self.binary_map)  # No structure parameter specified

When scipy.ndimage.label() is called without the structure parameter, it defaults to:

structure = _morphology.generate_binary_structure(input.ndim, 1)  # 1-connectivity

Expected Behavior

The method should respect the connectivity parameter passed during class initialization, similar to how other methods in the class use self.connectivity.

Evidence of Inconsistency

1. Class initialization accepts connectivity: 1

2. Other methods use connectivity: Other methods in the codebase properly use the connectivity parameter, as seen in 3

3. Real usage expects different connectivity: In practice, the class is instantiated with different connectivity values, such as neigh=6 in 4

Proposed Solution

Modify the foreground_component() method to use the stored connectivity parameter:

def foreground_component(self):
    structure = generate_binary_structure(self.binary_map.ndim, self.connectivity)
    return ndimage.label(self.binary_map, structure=structure)

Impact

This inconsistency may lead to unexpected results in connected component analysis, especially for users who expect the specified connectivity to be applied consistently across all morphological operations.