WWCC for two efBm maps (shown in a), maximum-filtered on scales of 15 pix and 5 pix) generated with a S/N = 5. The second efBm is shifted by τ_i = 14.1 pix (τ_i,x = 10 pix and τ_i,y = 10 pix). Part b) shows the Δ-variance spectra of the first map (full line) and the second map (dotted line) with marks of critical scales (l_c = 6.4 pix and l_c = 3 pix, full and dotted vertical lines, respectively) calculated from their noise-corrected spectra; c) the correlation coefficients; and d) the measured displacement vectors as a function of scale.