``3D_conn_comp'' - three-dim. connected components analysis

VFX name:

iConnComp3d

IMPROMPTU Equivalent:

3D_conn_comp

purpose:

This is a package of 3-D topological operations geared toward locating, labeling, and deleting connected sets of 1's [28]. A connected set of 1's is referred to as a connected component and the general set of operations packaged here is referred to as connected component analysis [24]. The specific operations possible here are

1.

Delete overly small components.

2.

Save a specified maximum number of components.

3.

Save component labels. The labels help to distinguish various objects.

The function ``iConnComp2d'' performs the analogous operations on 2-D x-y planes of a volume.

input:

An 8-bit binary-valued volume.

output:

An 8-bit volume, possibly grayscale-valued.

parameters:

Default parameters menu is

minCompSize = 10
maxNumComp = 1
connectivity = 6
saveLabels = No

The ``minCompSize'' restricts the minimum size in voxels of saved components; all components smaller than this number are deleted (set to 0).

The ``maxNumComp'' option determines how many components to save. If this parameter is set to 5, for example, only the 5 largest components are saved - all others are deleted. If you only want to save the largest connected component, set this parameter to 1.

The option ``connectivity'' sets the connectivity requirement of connected components. The options are ``6'' (for 6-connected) and ``26'' (for 26-connected) [28,23].

The ``saveLabels'' option toggles between ``Yes'' and ``No''. When the option is set to ``No'', only actions involving deleting components are done (per the settings of the parameters ``minCompSize = '' and ``maxNumComp''). If the option is set to ``Yes'', each different component will be assigned a unique number between 2 and 255; i.e., the component labeled 2 will have all of its voxels set to 2, etc.

comments:

1.

A medium-speed function, taking about 2 minutes in a typical 100x100x100 volume. 26-connectivity takes roughly twice as long as 6-connectivity.

2.

Only a maximum of 254 components can be saved safely within the volume!