Abstract: A method and apparatus for measuring the outer diameters, ovality and eccentricity of the finish of a container is disclosed. The invention can be practiced in either a one-camera or a two-camera embodiment. The one-camera embodiment comprises means for illuminating the finish with a collimated beam of light to produce a transmitted beam containing a shadow of the finish and means for focusing the transmitted beam containing the shadow of the finish to produce the image thereof. The apparatus further comprises a line-scan camera for periodically scanning sequential segments of the image from one periphery to the other periphery as the container rotates for providing a plurality of pixel signals for each scan, and a data circuit responsive to the magnitudes of the pixel signals in each of the scans for counting the number of signals in the peripheries of the image to provide a left periphery count and a right periphery count for each scan.