2D Gaussian structures injected on top of an fBm image with β = 2.4. he fBms are shifted to positive values by adding an arbitrary constant and normalized by their mean values. The maps have a resolution of 1000 × 1000 pixels. The 2D Gaussian functions all have an aspect ratio (f = σ₁∕σ₂ = 1) and a contrast between the peak of the Gaussian and the mean value in the map of δ_c = 3. The standard deviations of the 2D Gaussians are σ₁ = σ₂ = 10 pixels. All maps are normalized to their mean value. The maps correspond to the case of a single 2D Gaussian (bottom left), a number of 2D Gaussians (top left), an inverted 2D Gaussian (bottom mid), a number of inverted 2D Gaussians (top middle), and a mix of 2D Gaussians and inverted 2D Gaussians (top right). The corresponding Δ-variance functions calculated for each case are displayed in the bottom right subpanel, and they are compared to the Δ-variance function of the underlying fBm image as well to the case of the same fBm smoothed with a Gaussian beam whose FWHM is 6 pixels.