Chapter 3 Speckle Noise Reduction and Enhancement for OCT Images Zahra Amini, Raheleh Kafieh and Hossein Rabbani The OCT imaging produces speckle noise due to multiple forward and backward scattered waves. The most important step of OCT preprocessing is noise reduction, which is helpful for more sophisticated processes like segmentation. Three OCT despeckling and enhancement methods are presented in this chapter, which are based on statistical modeling, data adaptive and non data adaptive transform based models, respectively. 3.1 OCT Background Noninvasive methods for determination of anatomic information are of interest for many years. Some familiar methods are magnetic resonance imaging (MRI), com- puted tomography (CT scan) and ultrasound. Optical Coherence Tomography (OCT) is recently introduced to replace the ultrasound source with infrared light source and measure reflectance properties of tissue [1]. Each reflectance beam is called A-scan and a row of these beams make 2 dimensional B-scans. Series of such 2D images can be combined to produce a 3D volumetric measure of the anatomical area. Trans- parent anatomy of the retina to OCT energy source (light), makes this tissue a nice place to be scanned by this method. This transparency is easy to be understood since the light beam needs to pass through the whole retina to reach photoreceptors (on posterior surface) which have the responsibility of turning the light to electric signal of the brain. Figure 3.1 depicts the standard OCT scheme. Z. Amini · R. Kafieh · H. Rabbani (B ) Department of Bioelectrics & Biomedical Engineering, School of Advanced Technologies in Medicine, Medical Image & Signal Processing Research Center, Isfahan University of Medical Sciences, Isfahan, Iran e-mail: hoss_rab@yahoo.com © Science Press and Springer Nature Singapore Pte Ltd. 2019 X. Chen et al. (eds.), Retinal Optical Coherence Tomography Image Analysis, Biological and Medical Physics, Biomedical Engineering, https://doi.org/10.1007/978-981-13-1825-2_3 39