Test of the methods on different sets of simulated signals. A translating Gaussian function is considered. (A) Different velocities and directions of propagation were simulated, considering 10 images. The algorithm was applied either on the whole set of images (N = 10), or under-sampling by a factor 3 (N = 4, maintaining the same initial and final image, as shown in (A), lower panel). Ten realizations of Gaussian noise were added over the maps, with SNR of 10 or 20 dB. Estimates of the velocity are shown in (B), superposing curves corresponding to different angles obtained averaging with respect to the noise realization and indicating the standard deviation (STD). Estimates of the angle of the velocity are shown in (C).