How to find boundary(last 2 cycles) of image having more than 10 cycles?

Area of repetitive figure but small difference in each line?

[Image Analyst]

Huh? Where did you upload your image to? http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer All I can say now, considering what you've given me, is "use image processing" which is obviously no help at all.