I need your help to detect the radius of the blue circle in images like this:
imga=Import[http://i.stack.imgur.com/moV5x.png]; circle = SelectComponents[ MorphologicalComponents[ LaplacianGaussianFilter[ColorNegate@imga, 2], 0.003`], "Count", # > 400 &]; Colorize[circle]
And I have this output:
And now I'm stuck, if the circle were closed it would be simple, how can I find the best circle completing it? Obviously if you have a completely different solution it is fine (for example I thought it could be possible to take only the left semicircle, but I don't know how to do it).
Please note that I have to process about 100 images like that so if possible I would need the program to run in a reasonable amount of time and with no manual adjustments.
As a bonus question: since I have to determine also a possible error on the radius, would it be possible to find the outer and the inner circles? and the eccentricity of the closed figure (if it is possible to close it)?
P.S.: since I just started working with mathematica for image processing I would also like to know a few good references or books about it. I have read a few mathematica books but none of them treated this argument in detail.