finding the bending angle or change in curvature of line

in my Image there is one thin line which has some curvature/bending I want to find the that bending angle/change in curvature in that line i have to take grid lines which is there in image for reference can any one suggest me any idea how should i find and if anyone can provide me the solution it will be better here is image

[Rik]

Is the fine line the data you want to find the curvature for? That will be very noisy.

Anyway, I think the first step would be to undo the keystone (so the grid becomes square again). There are some solutions available when I searched for them about a year ago, so you should be able to find them as well.

[praveen rai]

ya i want to find curvature of that fine line.I know its noisy I want mathmatically solution some idea how should I find If u can provide me any link

[praveen rai]

@ John D'Errico dis is not do it for me somethng like that I want some idea from any one