how to detect center of a blurry circle with opencv

Question

I have got the following image:

There are curves on the picture. i would like to find center of the circles containing curves.

i tried opencv and hough circle transform but had no results.

Answer 1

The natural candidate would be cvHoughCircles. Each part of each curve adds a "vote" for an X/Y/R triplet which identifies the centrepoint. Now, you only have part of the circles, so the number of votes is limited and the accuracy reduced, but you probably suspected as much.