Correlation between the concentration index and the Sérsic index for the EGS images. The dot-dashed black curve is the numerical relationship derived by integrating the best-fit Sérsic model out to 1.5R_p. The solid purple curve is the empirical relationship of Eq. (5). The colour of the points marks the relative size of the galaxies (R_e/FWHM). The data points generally agree with the numerical expectation, but showing large scatters, especially for the galaxies with smaller relative sizes (R_e/FWHM ≤ 1).