Fienup algorithm

The Fienup algorithm is a technique used in optics and imaging to reconstruct a complete image from partial or indirect measurements, often when the phase information is missing. It works by iteratively guessing a solution, then refining it: starting with an initial estimate, it enforces known constraints in the image and measurement domains, gradually improving the reconstruction. Essentially, it alternates between adjusting the image estimate to match measured data and conform to physical constraints, converging on a plausible full image. This method is especially useful in fields like microscopy and astronomy, where directly capturing all information is challenging.