Upper panel: modulus of the m = 2 Fourier spectrum obtained from an r band image of the galaxy NGC 4535. This modulus has considerable substructure, due to the presence of many components. We superimpose using a dotted line the Gaussian fit, obtained as described in the text. Lower panel: difference between the value of the m = 2 modulus and the Gaussian fit. This fit, whose quality is typical for our sample, reproduces very well the m = 2 modulus, in spite of the latter’s complexity.