regionGrowing.md

Region Growing

Introduction

Given a grayscale image & a seed pixel location ( with in that image ), we'll try to segment this image using region growing mechanism.

• At very beginning, we'll have only seed pixel as active pixel
• In each of next iteration, we'll pick up inactive N8 ( pixels in order-1 neighbourhood ), of current pixel under inspection
• Each of selected N8 to be made active, so that in next iteration we don't include it again
• If current pixel, is having intensity value within specified range, we'll simply add make it dead pixel

Dead pixels to be included in sink image i.e. segmented image & they will be allowed to keep their intensity value as it was in original.

All other pixels to be made black i.e. rgb(0, 0, 0), that's selected background color.

We'll keep processing until we've zero active pixels in buffer.

Selection of seed pixel is very important for good segmentation result.

Usage

• Code for applying region growing based segmentation

// Main.java in some project, in which in.itzmeanjan.filterit.jar is set as dependency

import in.itzmeanjan.filterit.ImportExportImage;
import in.itzmeanjan.filterit.segmentation.RegionGrowing;


public class Main{

	public static void main(String [] args){
		System.out.println(
            ImportExportImage.exportImage(
                new RegionGrowing().segment("mask.png", 640, 452, 5),
                "segmented.png"));
	}

}

• Compile & run ( make sure in.itzmeanjan.filterit.jar is set as project dependency )

Result

In example below, sample image is of dimension 1280 x 904, so I used center pixel i.e. (640, 452) as seed pixel, so that MASK can be segmented.

Sample	Segmented

Thanking you 😊