Rotational Filtering for Fringe Patterns, Four-Step Phase-Shifting Method Implementation, and Multi-Frequency Heterodyne Algorithm Programs

This article introduces three algorithms for image processing applications. First, the rotational filtering algorithm can be applied to process fringe patterns - by implementing directional filtering through image rotation and frequency domain operations, this method effectively extracts characteristic information from fringe patterns. Second, the four-step phase-shifting method program enables precise phase measurement of images; through acquiring four phase-shifted images with π/2 intervals and applying arctangent calculations, this approach accurately determines phase information to reconstruct object shapes and surface height data. Finally, the multi-frequency heterodyne algorithm program facilitates 3D reconstruction in structured light projection systems; by processing multiple sets of fringe patterns with different frequencies and implementing frequency unwrapping techniques, this method reliably restores complete 3D shapes of objects. These algorithms demonstrate significant practical value in the field of image processing and optical metrology.