11.18. ITK Connected Component Image Filter

Labels each connected object in a binary image with a unique integer.

Group (Subgroup)

ITKConnectedComponents (ConnectedComponents)

Description

This filter performs connected components labeling: it labels each group of touching non-zero pixels with a unique consecutive integer (0 = background). Non-zero pixels are treated as object material and zero-valued pixels as background. Every distinct touching cluster of object pixels receives its own integer label, so the output is a label image (one where each region has a unique integer value).

Labels are assigned consecutively starting at 1, with no gaps. The label numbers follow the raster scan order in which objects are first encountered, so the assigned numbers carry no meaning beyond identity. To order the labels by object size instead, pass the output to the ITK Relabel Component Image Filter, which renumbers them so that label 1 is the largest object.

Use this filter when you have a thresholded (binary) image and need to identify and count the individual objects within it.

Parameter Guidance

  • Fully Connected — controls connectivity. Off uses face-only connectivity (pixels touch only across shared faces). On uses face+edge+corner connectivity, so objects that touch only diagonally are merged into one. Turn this On for objects that are 1 pixel wide or that connect along diagonals.

Required Input Sources

A binary image (cell data on an Image Geometry) where object pixels are non-zero and background pixels are zero, typically produced by a thresholding filter.

Input Parameter(s)

Parameter Name

Parameter Type

Parameter Notes

Description

Fully Connected

Bool

Set/Get whether the connected components are defined strictly by face connectivity or by face+edge+vertex connectivity. Default is FullyConnectedOff. For objects that are 1 pixel wide, use FullyConnectedOn.

Input Cell Data

Parameter Name

Parameter Type

Parameter Notes

Description

Image Geometry

Geometry Selection

Image

Select the Image Geometry Group from the DataStructure.

Input Cell Data

Array Selection

Allowed Types: int8, uint8, int16, uint16, int32, uint32, int64, uint64

The image data that will be processed by this filter.

Output Cell Data

Parameter Name

Parameter Type

Parameter Notes

Description

Output Image Data Array

DataObjectName

The result of the processing will be stored in this Data Array.

Example Pipelines

DREAM3D-NX Help

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