How to compute the edge of a binary graph

[zwpless]

• Is there code reference?

[zwpless]

• Is there a code reference

[altenbach]

You have posted three time with the same single sentence in the body of the post. This is NOT the right way to get help!

• Explain in detail what you want to do.
• Attach an example of your graph or image.
• Show us what you tried. 

[zwpless]

After I have processed the image and generated the binary image, how do I determine the coordinates of the points on the image contour to further calculate the straightness of the image contour (curve),

• The picture is roughly a curved cylinder

[altenbach]

What's the definition of "straightness"?

You could fit all points below a certain grey threshold to a circle. The radius can be used to derive a measure of straightness, the bigger, the straighter. 

Looks like a simple greyscale picture. I have no idea why you keep calling it "binary". (Everything on a computer is binary one way or another!)