How to detect random shapes and color changes on the moving object

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C#

image-processing

shape

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Dear all,

This is for the my new project so i need suggestion about how to start.

I want to detect random shape defects and color changes on the fax paper. For example there is a randomly shaped torn area on the paper. I want to find this region while the paper is moving or there is a certain color change on the apper i want to find this.

My first idea is to apply edge detection like canny and then finding the contours. But the question in my head is how to find randomly shaped defects coming from production of the paper. There are a lot of example for square, triangle and circle but i did not see any for random shapes.

For the color detection, i am planning to find color of the pixels of the paper before starting the paper movement then compare color change in every pixels. Is it good idea? Because random cameras scan an area not a line. Do i need line scan camera instead of regular camera. I am not sure about how good lighting i need. I think it should be really stable wihch requires closed area.
Do you have any other suggestion?

What I have tried:

I have not tried anything yet due to wthink about the porject. Any suggestion i welcome.