Figure 2.

Analyzing the corneal whorl pattern using whorl metrics. (A) Perpendicular vectors point toward the center of a spiral. (B) Creating traces by connecting the vectors and recording where traces end in the endpoint diagram. (C) The whorl area is the total image area that is connected by a trace to the whorl center. (D) The whorl standard deviation is calculated based on the distances (d_i) of each endpoint (with area w_i) with respect to the whorl center. (E) By following traces for n step outward from the center, the step-out area (E₁, blue) is compared to the ideal isotropic step-out (E₁, orange). The spiral fill score (E₂) is the overlap between the actual and ideal step-out. The spiral isotropic score (E₃) is the coefficient of variance calculated from 45 degree slices with area a_i of the step-out.