Flow chart of the three shallow U-Net models. Photospheric intensity and vertical magnetic field (B_z) data are from the numerical simulation detailed in the main text. Three models are illustrated in this flow chart. Model 1 (intensity model) takes three consecutive frames of the photospheric intensity as input. Model 2 (magnetic model) takes three successive frames of the photospheric vertical magnetic field strength as input. Model 3 (hybrid model) combines the inputs and outputs of Model 1 and Model 2 as its input. The outputs of the three models are images with two channels; the first channel is the velocity field along the x direction (v_x) and the second channel is the velocity field along the y direction (v_y). Here, δt represents the cadence of the data (10 s). Subscripts i, m, and h denote outputs of the intensity, magnetic, and hybrid models, respectively.