Introduction of C/A (covariance/area) with applications to tooth segmentation in dental CT image

We introduce a coordinate-dependent characteristic of symmetry, which is denoted by C/A. C/A is defined by the division of the covariance (C) by the area (A) of the object of the image. The characteristic has the good properties for the applications to the image processing. We compute the characteristic of ellipse, for which we derive the formula of the perimeter of ellipse. We apply C/A to the segmentation of tooth in a dental CT image.