Robust phase retrieval with complexityguidance for coherent Xray imaging
Abstract
Reconstruction of a stable and reliable solution from noisy incomplete Fourier intensity data recorded in a coherent Xray imaging (CXI) experiment is a challenging problem. The Relaxed Averaged Alternating Reflections (RAAR) algorithm that is concluded with a number of Error Reduction (ER) iterations is a popular choice. The RAARER algorithm is usually employed for several hundreds of times starting with independent random guesses to obtain trial solutions that are then averaged to obtain the phase retrieval transfer function (PRTF). In this paper, we examine the phase retrieval solution obtained using the RAARER methodology from perspective of the complexity parameter that was introduced by us in recent works. We observe that a single run of the RAARER algorithm produces a solution with higher complexity compared to what is expected based on the complexity parameter as manifested by spurious high frequency grainy artifacts in the solution that do not seem to go away completely even after a number of trial solutions are averaged. We then describe a CGRAAR (Complexity Guided RAAR) phase retrieval method that can effectively address this inconsistency problem and provides artifactfree solutions. The CGRAAR methodology is first illustrated with simulated unblocked noisy Fourier intensity data and later applied to centrallyblocked noisy cyanobacterium data which is available from the CXIDB database. Our simulation and experimental results using CGRAAR suggest two important improvements over the popular RAARER algorithm. The CGRAAR solutions after the averaging procedure is more reliable in the sense that it contains smallest features consistent with the resolution estimated by the PRTF curve. Secondly, since the single run of the CGRAAR solution does not have grainy artifacts, the number of trial solutions needed for the averaging process is reduced.
 Publication:

arXiv eprints
 Pub Date:
 May 2022
 arXiv:
 arXiv:2205.04094
 Bibcode:
 2022arXiv220504094B
 Keywords:

 Electrical Engineering and Systems Science  Image and Video Processing;
 Physics  Medical Physics