IOP PUBLISHING LASER PHYSICS LETTERS
Laser Phys. Lett. 10 (2013) 035603 (5pp) doi:10.1088/1612-2011/10/3/035603
LETTER
Application of RPCA in optical coherence
tomography for speckle noise reduction
F Luan
1
and Y Wu
2
1
College of Information Science and Engineering, Northeastern University, Shenyang, 110819,
People’s Republic of China
2
School of Materials and Metallurgy, Northeastern University, Shenyang, 110819,
People’s Republic of China
E-mail: luanfeng1979@hotmail.com
Received 27 March 2012
Accepted for publication 4 December 2012
Published 24 January 2013
Online at stacks.iop.org/LPL/10/035603
Abstract
Optical coherence tomography (OCT) is a promising technology, which could be used in a
variety of imaging applications. However, OCT images are usually degraded by speckle noise.
Speckle noise reduction in OCT is particularly challenging because it is difficult to separate
the noise and the information components in the speckle pattern. In this study, a novel speckle
noise reduction technique, based on robust principal component analysis (RPCA), is presented
and applied to OCT images for the first time. The proposed technique gives an optimal
estimate of OCT image domain transformations such that the matrix of transformed OCT
images can be decomposed as the sum of a sparse matrix of speckle noise and a low-rank
matrix of the denoised image. The decomposition is a unique feature of the proposed method
which can not only reduce the speckle noise, but also preserve the structural information about
the imaged object. Applying the proposed technique to a number of OCT images showed
significant improvement of image quality.
(Some figures may appear in colour only in the online journal)
1. Introduction
Optical coherence tomography (OCT) is a modern biomedical
imaging technology based on low coherence interferometry
(LCI). OCT allows for non-contact, high-resolution imaging
of biological tissues [1]. Over the past 20 years, OCT’s
development has been remarkable. With rapid progress, OCT
is now often cited as a promising tool, which could be
used in a variety of imaging applications. Since OCT is
based on detection of coherent waves, OCT images contain
speckle. Speckle in OCT is dependent on the wavelength of
the imaging beam and the structural details of the imaged
object [2]. Time varying speckle in OCT structural images
can be used in the analysis of tissue structure and flow
information [3–5]. In [6] it is mentioned that the speckle
content present in depth OCT images can be utilized to
differentiate various tissue types, such as skin, lung, fat
and breast tissue. The speckle variance OCT method can
also be used to delineate tissue micro vasculature in vivo
according to its different temporal speckle decorrelation
characteristics [7, 8]. Speckle variance imaging provides a
more accurate representation of the vascular structure [9].
As mentioned above, we believe that there are information
components representative of the imaged object in the
speckle pattern. Unfortunately, speckle also carries a noise
component, which is responsible for the grainy appearance
of OCT images [10–12]. Reduction of speckle noise can
increase the image contrast and spatial resolution, therefore
allowing further visualization of the imaged object [13].
However, speckle noise reduction in OCT is particularly
challenging because it is difficult to separate the noise and the
information components in the speckle pattern [10–12]. Much
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