2D Gaussian structures injected on top of an fBm image with β = 2.4. The 2D Gaussian functions have an aspect ratio (f = σ₁∕σ₂) that is varied in the range [1–10], and all have a value of δ_c = 5 and a fixed size of σ₁ = 50 pixels. All maps are normalized to their mean value. Bottom-right figure: corresponding Δ-variance functions calculated for each case, and these are compared to the Δ-variance function of the underlying fBm image.