Impact Of Speckle Noise Research Articles

Coherent correlator design analysis for the implementation of deep learning networks.

Optical signal processing can reduce the electrical power consumption required over that required by graphically processing units. There remain a number of challenges to overcome. Noise is potentially much larger in optical systems than in their electronic counterparts, and some of the operations, such as a bias addition, are not easy to implement in free space processors. This paper analyzes a proposed design that utilizes a camera and lightweight electronic processing to perform the convolutional layers. Simulations are performed to compare the expected performance against an ideal system that cannot be physically realized and a proposed architecture. The impact of speckle noise in the system is analyzed and methods to reduce this are proposed.

Edge-Preserving classification of polarimetric SAR images using Wishart distribution and conditional random field

ABSTRACT Classification of polarimetric SAR images into different ground covers has important applications in fields such as land mapping, agriculture monitoring, and assessment. The Wishart supervised classifier is one of the most widely used and general purpose classifier for polarimetric SAR data. However, it is a pixel-based classifier, so the performance is greatly affected by inherent speckle noise. The impact of speckle noise can be reduced by considering the spatial information from neighbouring pixels for classification tasks. In this paper, we aim to improve classification results by incorporating spatial-contextual information along with preservation of significant details such as edges and micro-regions. For this purpose, a conditional random field (CRF) based model is proposed for polarimetric SAR data along with Wishart and Wishart mixture model (WMM) classifiers, namely Wishart-CRF and WMM-CRF, to perform the classification. The model is compared with the Markov random field (MRF) based model as well as neural network-based models. The results are analysed in terms of accuracy and preservation of details such as edges and micro-regions. The model is assessed using three full polarimetric SAR benchmark data sets. The CRF model exhibits better classification results by significantly reducing the noise and preserving the finer details of edges and small regions.

An improved neighborhood-based ratio approach for change detection in SAR images

ABSTRACTThe speckle noise of synthetic aperture radar (SAR) images limits its application in change detection. Compared with improved ratio (IR) and log-ratio (LR) operators, the neighborhood-based ratio (NR) technique can restrain the influence of speckle noise and is more suitable for change detection in SAR images. However, we find three drawbacks of NR by analyzing this method carefully. To overcome these defects, we propose an improved neighborhood-based ratio (INR) approach for change detection in SAR images. INR restructures the NR operator to exploit the neighborhood information more reasonably and is expected to reduce the impact of speckle noise better. IR, LR, mean ratio operator, NR, and INR are tested on two data sets to compare their performances in change detection of SAR images. Experimental results show that the proposed method can obtain better difference image than other state-of-art methods and improve the accuracy of change detection in SAR images effectively.

Detection of Intima-Media Thickness in Common Carotid Artery on Ultrasound Image

The intima-media thickness (IMT) measurement is an important subject in the cardiovascular disease diagnosis. However, the manual way to measure IMT is not objective and imprecise due to the skill of the operators. In this paper, a new method of automatic IMT measurement is proposed. This algorithm solves the active contour model problem based on the modified dynamic programming to search the most minimize cost path which is the contour of the intima-media. Experimental results demonstrate that this method is not only robust for the impact of speckle noise, but also attain better extraction results than the traditional way with much smaller time-consuming. The clear intima-media could be automatically obtained with a simple and not very select ROI.

散斑噪声对相干激光雷达系统性能的影响

散斑噪声对相干激光雷达系统性能的影响