Computer Vision Demonstration Website

Electronics and Computer Science
University of Southampton

Sobel Edge Detection

The Sobel operator is a classic first order edge detection operator that finds contrast by a process akin with differentiation. Here we detect the magnitude of the edges by convolving two 3*3 templates with the grey level image.

How it works

Sobel calculates not only the magnitude of the edges, but also their direction. The operator uses a 3x3 template horizontally then vertically:

The resulting image uses pythagoras to generate the magnitude of the edges and inverse tan to get the direction of the edges.

Code

Image processing classes:

• sobel.java

Demo framework:

• sobelDemo.java

The pages were designed and developed for educational purposes only, to demonstrate how computer vision techniques work. They are designed for no other purpose and neither the authors nor their institutions accept any liability concerning use of these pages.

Links

Mark Nixon & Alberto Aguado, 2002, Feature Extraction & Image Processing, Newnes

ECS | Feature Extraction & Image Processing | © 2005 University of Southampton