Artificial example of a scale-by-scale wavelet cross-correlation analysis. Top:two different mock maps before the wavelet decomposition. The maps show four large-scale spots made by small-scale spots. The large-scale spots in the two maps slightly differ in size (6 rows and columns in the right panel, 5 rows and columns in the left panel). As they are centered at the same location, the small-scale spots are shifted with respect to each other. Bottom left: wavelet spectra (they are identical for both maps), bottom right: wavelet cross-correlation function.