A nonlocal deep image prior model to restore optical coherence tomographic images from gamma distributed speckle noise

2021 ◽  
Vol 68 (18) ◽  
pp. 1002-1017
Author(s):  
A. Smitha ◽  
P. Jidesh
2014 ◽  
Vol 875-877 ◽  
pp. 1982-1988
Author(s):  
Wen Liang Du ◽  
Xiao Lin Tian ◽  
Yan Kui Sun

Speckle noise is a common phenomenon in Optical Coherence Tomography (OCT) images. This paper describes a dynamic filtering approach for anterior chamber OCT images to reduce the speckle noise in wavelet domain. The approach proposed segments the OCT image into some parts and identifies if the parts have region of interest (ROI), which includes the anterior chamber tissues. Then, it suppresses noise with three different suppression strategies in part with ROI. For the part without ROI, it sets the discrete wavelet transform coefficients of this part to zero. Here, the sampling-based sub-band adaptive algorithm is used to distinguish the ROI; and the correlations of neighboring wavelet coefficients and the coefficients of the corresponding locations in adjacent decomposition levels are used to suppress the noise. The performance improvement over the previously published method is quantified in terms of noise suppression, image structural preservation and visual quality. The numerical values of the image quality metrics along with the qualitative analysis results indicated that the approach proposed has better performance.


Electronics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 52
Author(s):  
Richard Evan Sutanto ◽  
Sukho Lee

Several recent studies have shown that artificial intelligence (AI) systems can malfunction due to intentionally manipulated data coming through normal channels. Such kinds of manipulated data are called adversarial examples. Adversarial examples can pose a major threat to an AI-led society when an attacker uses them as means to attack an AI system, which is called an adversarial attack. Therefore, major IT companies such as Google are now studying ways to build AI systems which are robust against adversarial attacks by developing effective defense methods. However, one of the reasons why it is difficult to establish an effective defense system is due to the fact that it is difficult to know in advance what kind of adversarial attack method the opponent is using. Therefore, in this paper, we propose a method to detect the adversarial noise without knowledge of the kind of adversarial noise used by the attacker. For this end, we propose a blurring network that is trained only with normal images and also use it as an initial condition of the Deep Image Prior (DIP) network. This is in contrast to other neural network based detection methods, which require the use of many adversarial noisy images for the training of the neural network. Experimental results indicate the validity of the proposed method.


2021 ◽  
Author(s):  
Li Ding ◽  
Yongwei Wang ◽  
Xin Ding ◽  
Kaiwen Yuan ◽  
Ping Wang ◽  
...  
Keyword(s):  

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Damian Siedlecki ◽  
Waldemar Kowalik ◽  
Henryk Kasprzak

Purpose. The aim of the study is to demonstrate that the ocular dynamics of the anterior chamber of the eye can be estimated quantitatively by means of optical coherence tomography (OCT).Methods. A commercial high speed, high resolution optical coherence tomographer was used. The sequences of tomographic images of the iridocorneal angle of three subjects were captured and each image from the sequence was processed in MATLAB environment in order to detect and identify the contours of the cornea and iris. The data on pulsatile displacements of the cornea and iris and the changes of the depth of the gap between them were retrieved from the sequences. Finally, the spectral analysis of the changes of these parameters was performed.Results. The results of the temporal and spectral analysis manifest the ocular microfluctuation that might be associated with breathing (manifested by 0.25 Hz peak in the power spectra), heart rate (1–1.5 Hz peak), and ocular hemodynamics (3.75–4.5 Hz peak).Conclusions. This paper shows that the optical coherence tomography can be used as a tool for noninvasive estimation of the ocular dynamics of the anterior segment of the eye, but its usability in diagnostics of the ocular hemodynamics needs further investigations.


2012 ◽  
Vol 20 (2) ◽  
pp. 1337 ◽  
Author(s):  
Maciej Szkulmowski ◽  
Iwona Gorczynska ◽  
Daniel Szlag ◽  
Marcin Sylwestrzak ◽  
Andrzej Kowalczyk ◽  
...  

Author(s):  
Fangshu Yang ◽  
Thanh-an Pham ◽  
Nathalie Brandenberg ◽  
Matthias P. Lutolf ◽  
Jianwei Ma ◽  
...  

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