Fig. 6.

Errors in CR center localization for the three methods as a function of CR radius for different noise levels (top-left), pixel intensity levels of the lighter background section (top-right), locations of the gray background (bottom-left) and Gaussian amplitudes (bottom-right). For the top-left panel, average error of the radial symmetry method ranged from 3–8 pixels at noise level 18, not shown. For the top-right and bottom panels, the noise level was 0. For the bottom panels, the pixel intensity level of the lighter background section I was 128. For the bottom-right panel, the background location E was 0