Tutorial of Motion Estimation Based on Horn-Schunk Optical Flow Algorithm in MATLAB®

The Horn-Schunk algorithm (HS) is one of the classical algorithms in optical flow due to its reasonable performance and simplicity of the algorithm. This article presents in detail the process of the HS algorithm and its step by step coding in MATLAB® . The HS algorithm is a technique used to identify the image velocity or motion vector based on Spatial Temporal Gradient Technique which computes the image velocity from spatiotemporal derivatives of image intensity. Firstly, the original estimated intensity for gradient constraint on the image sequence is obtained by using the gradient constraint with a global smoothness. Then, iterative equations are solved to minimize the sum of the errors for the rate of change of image gradient intensity and obtain the image velocit