Image Segmentation using Unsupervised Watershed Algorithm

img. segment

ABSTRACT

Image segmentation is the process of partitioning an image to meaningful segments. There are many segmentation algorithms available, but nothing works perfect in all the cases. In computer vision, Image segmentation algorithms available either as interactive or automated approaches. In medical imagine, interactive segmentation techniques are mostly used due to the high precision requirement of medical applications. But some applications like semantic indexing of images may require fully automated segmentation method.

Automated segmentation methods can be divided into two categories namely supervised and unsupervised segmentation. In supervised segmentation the method use a machine learning technique to provide the knowledge of objects (or ground truth segments) in images to the segmentation algorithm.Unsupervised segmentation may use basic image processing techniques to complex optimization algorithms. Hence these segmentation methods take much more time when we ask for better results.


IMPLEMENTATION

Algorithm     :  OpenCV 2.4 and Visual C++ 
code to work:  C++.
           An implementation of unsupervised watershed algorithm for image segmentation with a histogram matching technique to reduce over-segmentation occurred by the segmentation algorithm.


CONCEPTS

  • Otsu Thresholding
  • Morphology - Opening
  • Distance Transformation
  • Watershed Segmentation Algorithm
  • Hue-Saturation Histogram
  • Histogram comparison.

SCREENSHOTS

                                                                    Original image

original image

After applying otsu's threshold 

threshold

After Morphology 

after morphology

After distance transformation 

image segment

 After Applying the Threshold to Distance Transformed Image 


After Applying Watershed Segmentation 

segmentation

Image in HSV Color Space  

hsv colour

The Segmentation after Merging 

merging

When the Merged Segmentation Mapped to Image 

mapped

SOURCE:www.codeproject.com