Given an input image pair, determine the velocity vector field using a recursive gradient-based image deformation algorithm based on Lucas-Kanade optical flow, adapted for the unique illumination characteristics of PIV images.
- Read image data (.tif, .png, other uncompressed formats?) from given filepath
- Read metadata (interframe time, pixel spacing) from configuration file
- Normalize/filter/clean image data
- Resample image at n ∈ N resolution levels, dividing the resolution by 2 each time
- Starting at the lowest-resolution image, determine & upsample displacement fields:
- Compute spatial intensity gradient of initial image
- Compute 2x2 minimization matrices H for each pixel
- Iteratively:
- Compute deformed image intensity from prior displacement estimate u₀
- Compute RHS vector c = (ΔI - ∇I u₀) ∇I
- Solve 2x2 system u = H⁻¹c for each pixel
- Upsample estimated displacement field to match the resolution of the next level
A working Julia installation is required: download the latest release for your platform here. If you'd rather not install anything, you can register for a JuliaBox account, which gives you free access to a remotely-managed Julia environment.
Several additional packages must also be installed; this is done by entering
the Julia command-line and typing Pkg.add("packagename"). To be sure everything
has been installed correctly, type versioninfo(true) in the Julia prompt.
The required packages are:
- Images
- ImageView
- Interpolations
- Plots
- Glob
Once the environment is properly configured, the code can be run by navigating
to the scratch/ directory and running include("repl.jl")
from the Julia prompt.