X-ray colors as in Iwasawa et al. (2012). Different symbols correspond to column densities from manual spectral fits: CT candidate (filled squares), near-CT (filled triangles), log (N_H) > 23 (empty squares), 22 < log (N_H) < 23 (filled circles), and log (N_H) < 22 (empty circles). Top-left: X-ray colors derived from manual spectral analysis. Top-right: colors obtained by using HEASARC PIMMS (see text for details). Bottom-left: colors obtained by using automated spectral fits. Bottom-right: colors obtained by using automated spectral fits for the sources not belonging to the sample of highly absorbed candidates.