Pixel-based speckle adjustment for noise reduction in Fourier-domain OCT images.

Anqi Zhang,Xingde Li,Jitao Sun,Jiefeng Xi

doi:10.1364/boe.8.001721

Anqi Zhang, Xingde Li + Show 2 more

Open Access

https://doi.org/10.1364/boe.8.001721

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Abstract

Speckle resides in OCT signals and inevitably effects OCT image quality. In this work, we present a novel method for speckle noise reduction in Fourier-domain OCT images, which utilizes the phase information of complex OCT data. In this method, speckle area is pre-delineated pixelwise based on a phase-domain processing method and then adjusted by the results of wavelet shrinkage of the original image. Coefficient shrinkage method such as wavelet or contourlet is applied afterwards for further suppressing the speckle noise. Compared with conventional methods without speckle adjustment, the proposed method demonstrates significant improvement of image quality.

Highlights

Optical coherence tomography (OCT) emerges as a powerful biomedical imaging modality providing depth-resolved information based on temporal coherence gating [1]
In this paper we propose a new speckle reduction method based on speckle adjustment for Fourier-domain OCT (FD-OCT) images
The results of applying the proposed method to an OCT fingertip image and a guinea pig esophagus image show superior performance of this new method comparing with the results of conventional speckle reduction methods without speckle adjustment

Summary

Introduction

Optical coherence tomography (OCT) emerges as a powerful biomedical imaging modality providing depth-resolved information based on temporal coherence gating [1]. Different from conventional speckle reduction methods that operate upon the whole data set, this method first identifies the pixels that impose the “grainy” appearance on the image degrade the image quality using the phase information of complex OCT signals [20]. Hereby we denote these pixels as noise pixels while the rest of the pixels as image pixels in this work. The results are compared with those using the same speckle reduction methods but without speckle adjustment

Method

Speckle detection and adjustment

Quantitative image quality metrics

Discussion and conclusions