Open AccessPhase retrieval method for in-line phase contrast x-ray imaging and denoising by regularization
Author(s) -
Ping-Chang Lee
Publication year - 2015
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.23.010668
Subject(s) - phase retrieval , phase contrast imaging , regularization (linguistics) , smoothing , optics , noise reduction , attenuation , computer science , algorithm , norm (philosophy) , filter (signal processing) , iterative method , linear filter , contrast (vision) , mathematics , artificial intelligence , phase contrast microscopy , physics , computer vision , fourier transform , mathematical analysis , law , political science
Phase contrast X-ray imaging is increasingly popular in the past decade. In order to acquire phase contrast X-ray images, different types of imaging mechanisms have been proposed. Among them, in-line phase contrast X-ray imaging shows the highest potential because of its simplicity. In the study of in-line phase contrast imaging, based on different physical assumptions, many non-iterative phase retrieval methods, such as Bronnikov method, modified Bronnikov method, phase-attenuation duality (PAD) method, single-material method, and two-material method have been proposed. The main step of the non-iterative methods is a filtering process, thus different methods involve different filter design. In this paper we showed that every filter applied in the methods listed above is indeed the minimizer of a L(2)-norm regularization problem. In addition, two methods were proposed to overcome the over smoothing problem owing to the nature of L(2)-norm regularization.