how to create a vision system that can detect the crack on outer part of the pipe line and also measure the width and length of crack?

The crack inspection is done with a vision system using webcam. The classification process has to follow the criteria given below:

The system has to inspect 3 types of crack with different dimensions. There 3 different types of crack, catastrophic crack, hair line crack (minimum 3mm width) and corrosion cracks. The vision system will capture video streaming from the webcam image and the inspection is done when crack is detected. The system must not be sensitive to colours, distance and orientation. The pipe can be gray or white.

[Image Analyst]

What does this have to do with the Coder or Simulink products?

Where is your image? Please read this. and see my image segmentation tutorials.