The Petrosian radius versus (gray) the semi-major axis length of the ellipse that contains half of the flux estimated from the CALIFA data cube through the curve of growth at 5635 Å; the radius () of the circle with equivalent flux to the ellipse (blue points); the half-light radius, (red points). The black line is the one-to-one line, while the dotted blue line is the fit to () and , and the dashed red line the fit to .