Test of the method following the Horn-Schunck approach on a simulated signal. Three Gaussian functions are considered: the first two propagate without shape changes, the third is stationary, but it grows in amplitude. Three sampled 2D maps are shown in (A)). A different number N of maps are considered, using the same initial and final conditions, but under-sampling by different factors. The estimated flow and growth are shown in (B1) and (C1), respectively, for the case in which 4 maps are considered, in (B2) and (C2) in the case in which 6 maps are used, and in (B3) and (C3) for the case in which 16 maps are processed.