Dependence of the peak region of the degree of anisotropy (upper plot), the spectra of isotropic wavelet coefficients, Mⁱ (central plot), and the quadratic-scale-normalized spectra of isotropic wavelet coefficients, Mⁱ ∕s² (lower plot), on the aspect ratio of the Gaussian ellipses. We changed the major axis σ_c of the ellipses while keeping the minor axis σ_a = 1 pixel constant. For every filter, three curves are plotted giving the location of the peak and the two plateau edges at 90% of the peak.