From the left to the right panels surface brightness, Petrosian ratio, and integrated flux. The upper(lower) row is obtained by using elliptical(circular) aperture and the iraf ELLIPSE(PHOT) task. For an effective radius, Re = 10 pixels, we estimated photometry in the case of a symmetric exponential profile (solid line), exponential profile with ellipticity equal to 0.5 and either position angle 0 (dashed line) or 45 (dotted line) degrees, and of a de Vaucouleurs profile (triangles). The case of adding noise is represented by filled circles with and without errorbars. The analytical Petrosian ratios for exponential (THEOexp) and de Vaucouleurs (THEOdeVauc) profiles are presented in the second-column panels as blue and cyan solid curves respectively.