Optical Flow Estimation from Monogenic Phase

The optical flow can be estimated by several different methods, some of them require multiple frames some make use of just two frames. One approach to the latter problem is optical flow from phase. However, in contrast to (horizontal) disparity from phase, this method suffers from the phase being oriented, i.e., classical quadrature filter have a predefined orientation in which the phase estimation is correct and the phase error grows with increasing deviation from the local image orientation. Using the approach of the monogenic phase instead, results in correct phase estimates for all orientations if the signal is locally 1D. This allows to estimate the optical flow with sub-pixel accuracy from a multi-resolution analysis with seven filter responses at each scale. The paper gives a short and easy to comprehend overview about the theory of the monogenic phase and the formula for the displacement estimation is derived from a series expansion of the phase. Some basic experiments are presented.