Surface plots, projected filled contour plots, and surface brightness distributions for 2D elliptical Sérsic images with (x₀,  y₀) = (0, 0), h_x = 4, and h_y = 2. θ and n are π/3 and 0.5 (top left), π/2 and 1 (top right), 2π/3 and 2 (bottom left). The surface brightness as a function of radius shown in the bottom-right panel is measured using elliptical annuli with the same rotation angle of these images. The radius is the one along the major axis. The black, red and blue dots are measured from the top-left, top-right, and bottom-left images, respectively. The black, red, and blue lines are the fits to these surface brightness distributions with 1D Sérsic function in Eq. B.1. The best-fitted Sérsic indices are labeled in the same colors as the fitting lines.