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Fast Checkerboard Demodulation for digital Schlieren imaging

version (25.8 KB) by S Wildeman
Track optical distortions in a checkerboard pattern with high accuracy in real-time using the FCD method


Updated 09 Dec 2018

GitHub view license on GitHub

Collection of functions for tracking optical distortions in a checkerboard pattern (or any other 2D periodic pattern) using 2D Fourier demodulation. Can be used for e.g. Synthetic/Background-oriented Schlieren (BOS) imaging or lens calibration. All functions are well documented and some usage examples are included.

- Robust full-field 2D distortion tracking with high dynamical range
- Can typically track displacements as small as 0.01 pixels and up to about 4 pixels (For larger displacements phase unwrapping may be required. A basic implementation for this is included.)
- Can resolve high virtual strains: up to about 0.7 px/px.
- Returns dense vector fields (one vector per pixel)
- Includes several schemes for integrating gradient fields (some of them support ROIs).
- Very fast due to extensive use of FFT
- Includes a live preview function
- Runs on GPU without modifications

More info:

Cite As

Wildeman, Sander. “Real-Time Quantitative Schlieren Imaging by Fast Fourier Demodulation of a Checkered Backdrop.” Experiments in Fluids, vol. 59, no. 6, Springer Nature, May 2018, doi:10.1007/s00348-018-2553-9.

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Comments and Ratings (1)

federigo ceraudo


updated citation info and extended description

updated github link

added a figure to the description

MATLAB Release Compatibility
Created with R2016b
Compatible with any release
Platform Compatibility
Windows macOS Linux