Connected components
Prerequisites
Before starting this lesson, you should be familiar with:
Learning Objectives
After completing this lesson, learners should be able to:
TODO
Motivation
Very often, one wants to detect objects or specific regions in images. After connected_components, the image is divided in background and foreground pixels. The next step is a connected components analysis, where spatially connected regions of foreground pixels are assigned as being part of one region.
Concept
graph TD
BI("Binary image") --> CC("Connected component analysis")
CC --> LI("Label image")
LI --> PV("Integer pixel values")
PV --> BG("0: Background")
PV --> R1("1: Region 1")
PV --> R2("2: Region 2")
PV --> R3("...")
Activity
Open a binary image and conduct a connected components analysis.
Show activity for:ImageJ GUI
- Open image: xy_8bit_binary__nuclei.tif
- Perform connected components analysis
- Explore multi-color LUTs for object labelling
- Explore removing and joining labels
KNIME
Formative assessment
Fill in the blanks, using these words: less, more, 8, 255, 4, more.
- In 3D, pixels have ___ neighbors than in 2D. 1. 8-connected connectivity results in ___ objects than 4-connected connectivity. 1. In 3D, pixels have __ non-diagonal neighbors. 1. In 2D, pixels have __ non-diagonal neighbors. 1. A 8-bit label image can maximally have ___ objects. 1. The maximum value in a label image is equal to or ___ than the number of objects.
Follow-up material
We recommend reading these modules next:
Learn more: