Many automatic visual inspection applications involve checking circular holes. In this paper four circularity measures based on shape compactness, distribution of radius values, distribution of chord lengths between random border points and the Hough transform are comparatively studied. Properties of the various approaches are investigated over a range of image resolutions which are considered to be pertinent to industrial inspection tasks.
"Measures of Circularit for Automatic Inspection Applications", Proc. SPIE 0557, Automatic Inspection and Measurement, (19 December 1985); doi: 10.1117/12.966266; https://doi.org/10.1117/12.966266