scholarly journals A comprehensive non-uniformity correction method for EMCCD

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Li Qiao ◽  
Mingfu Wang ◽  
Zheng Jin ◽  
Danbo Mao
Keyword(s):  
Characteristic Curve ◽  
Light Response ◽  
Response Characteristic ◽  
Correction Method ◽  
Correction Function ◽  
Correction Algorithm ◽  
Function Model ◽  
Output Image ◽  
Imaging Model ◽  
Photo Response

AbstractThe non-uniformity of image directly affects the application of EMCCD in various disciplines. The proposed method can significantly improve the uniformity of EMCCD output image. The correction algorithm of "reverse split and forward recovery" is determined through analyzing the imaging model of EMCCD, and the comprehensive non-uniformity correction function model is established. The 8-tap EMCCD chip CCD220 of British e2v company is used for experimental verification. The results show that after the comprehensive correction the consistencies of the light response characteristic curve and the multiplication gain curve of each channel in EMCCD are obviously improved, and also the photo response non-uniformity (PRNU) of the output image is substantially reduced from 24.5 to 4.1%, which prove the effectiveness of the proposed method.

scholarly journals Assessing an Atmospheric Correction Algorithm for Time Series of Satellite-Based Water-Leaving Reflectance Using Match-Up Sites in Australian Coastal Waters

2021 ◽  
Vol 13 (10) ◽  
pp. 1927
Author(s):  
Fuqin Li ◽  
David Jupp ◽  
Thomas Schroeder ◽  
Stephen Sagar ◽  
Joshua Sixsmith ◽  
...  
Keyword(s):  
Coastal Waters ◽  
Atmospheric Correction ◽  
Correction Method ◽  
In Situ Measurements ◽  
Landsat 8 ◽  
Correction Algorithm ◽  
Simple Method ◽  
North East ◽  
The Impact

An atmospheric correction algorithm for medium-resolution satellite data over general water surfaces (open/coastal, estuarine and inland waters) has been assessed in Australian coastal waters. In situ measurements at four match-up sites were used with 21 Landsat 8 images acquired between 2014 and 2017. Three aerosol sources (AERONET, MODIS ocean aerosol and climatology) were used to test the impact of the selection of aerosol optical depth (AOD) and Ångström coefficient on the retrieved accuracy. The initial results showed that the satellite-derived water-leaving reflectance can have good agreement with the in situ measurements, provided that the sun glint is handled effectively. Although the AERONET aerosol data performed best, the contemporary satellite-derived aerosol information from MODIS or an aerosol climatology could also be as effective, and should be assessed with further in situ measurements. Two sun glint correction strategies were assessed for their ability to remove the glint bias. The most successful one used the average of two shortwave infrared (SWIR) bands to represent sun glint and subtracted it from each band. Using this sun glint correction method, the mean all-band error of the retrieved water-leaving reflectance at the Lucinda Jetty Coastal Observatory (LJCO) in north east Australia was close to 4% and unbiased over 14 acquisitions. A persistent bias in the other strategy was likely due to the sky radiance being non-uniform for the selected images. In regard to future options for an operational sun glint correction, the simple method may be sufficient for clear skies until a physically based method has been established.

An Adaptive Response Surface Method Using Bayesian Metric and Model Bias Correction Function

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Lei Shi ◽  
Ren-Jye Yang ◽  
Ping Zhu
Keyword(s):  
Response Surface ◽  
Bias Correction ◽  
Adaptive Response ◽  
Large Scale ◽  
Correction Method ◽  
Data Uncertainty ◽  
Correction Function ◽  
Surface Model ◽  
Model Bias ◽  
Adaptive Response Surface Method

The Bayesian metric was used to select the best available response surface in the literature. One of the major drawbacks of this method is the lack of a rigorous method to quantify data uncertainty, which is required as an input. In addition, the accuracy of any response surface is inherently unpredictable. This paper employs the Gaussian process based model bias correction method to quantify the data uncertainty and subsequently improve the accuracy of a response surface model. An adaptive response surface updating algorithm is then proposed for a large-scale problem to select the best response surface. The proposed methodology is demonstrated by a mathematical example and then applied to a vehicle design problem.

STATISTICAL CHARACTERISTICS OF SLANT ANGLES IN HANDWRITTEN NUMERAL STRINGS AND EFFECTS OF SLANT CORRECTION ON SEGMENTATION

2010 ◽  
Vol 24 (01) ◽  
pp. 97-116 ◽  
Author(s):  
JAVAD SADRI ◽  
CHING Y. SUEN ◽  
TIEN D. BUI
Keyword(s):  
Efficient Method ◽  
Weighted Average ◽  
Correction Method ◽  
Statistical Characteristics ◽  
Geometric Features ◽  
Correction Algorithm ◽  
Connected Component ◽  
Slant Angle ◽  
Segmentation Accuracy ◽  
First Time

A novel and efficient method for correction of slant angles in handwritten numeral strings is proposed. For the first time, the statistical distribution of slant angles in handwritten numerals is investigated and the effects of slant correction on the segmentation of handwritten numeral strings are shown. In our proposed slant correction method, utilizing geometric features, a Component Slant Angle (CSA) is estimated for each connected component independently. A weighted average is then used to compute the String Slant Angle (SSA), which is applied uniformly to correct the slant of all the components in numeral strings. Our experimental results have revealed novel statistics for slant angles of handwritten numeral strings, and also showed that slant correction can significantly improve extraction of segmentation features and segmentation accuracy of touching numerals. Comparison between our slant correction algorithm and similar algorithms in the literature show that our algorithm is more efficient, and on average it has a faster running time.

Error Analysis and Compensation in Images Stitching for the Mechanically Stitched CCD Aerial Cameras

2019 ◽  
Vol 33 (09) ◽  
pp. 1955012
Author(s):  
Haipeng Kuang ◽  
Lina Zheng ◽  
Guoqin Yuan ◽  
Jianjun Sun ◽  
Zhuang Zhang
Keyword(s):  
Attitude Change ◽  
Correction Method ◽  
Monte Carlo Algorithm ◽  
Image Motion ◽  
Image Mosaic ◽  
Geometric Correction ◽  
Ccd Imaging ◽  
Imaging Model ◽  
Orientation System ◽  
Relationship Of

Image misalignment during image stitching is a common issue for the mechanically stitched CCDs in the aerial cameras due to the relative image motion between CCDs. In this paper, we analyze the error in imaging stitching for the mechanically stitched CCDs and propose a compensation method based on position and orientation system (POS). First, the imaging relationship of overlapping pixels in mechanical stitching is analyzed. The imaging model of adjacent CCD is constructed according to the collinear equation. The effects of stitching staggered distance, carrier attitude change and flight speed on the image mosaic of overlapping areas are given. Monte Carlo algorithm is used to analyze the statistical value of image mosaic error in overlapping area under typical working conditions. Then, a geometric correction method based on POS recording of external orientation elements of adjacent CCD imaging is proposed. The overlapping area stitching error is reduced from 14.9 pixels to 0.4 pixels which meets the engineering requirements. The mechanical stitching mathematical model, analysis and correction method established in this paper have strong engineering and application significance for mechanical stitching of aerial cameras.

scholarly journals Ultra-Widefield Fluorescein Angiography Image Brightness Compensation Based on Geometrical Features

Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 12
Author(s):  
Wojciech Więcławek ◽  
Marta Danch-Wierzchowska ◽  
Marcin Rudzki ◽  
Bogumiła Sędziak-Marcinek ◽  
Slawomir Jan Teper
Keyword(s):  
Image Quality ◽  
Fluorescein Angiography ◽  
Imaging Modality ◽  
Correction Method ◽  
Correction Function ◽  
Image Brightness ◽  
Geometrical Features ◽  
Noticeable Improvement ◽  
Manual Processing ◽  
Image Quality Measures

Ultra-widefield fluorescein angiography (UWFA) is an emerging imaging modality used to characterise pathologies in the retinal vasculature, such as microaneurysms (MAs) and vascular leakages. Despite its potential value for diagnosis and disease screening, objective quantitative assessment of retinal pathologies by UWFA is currently limited because laborious manual processing is required. In this report, we describe a geometrical method for uneven brightness compensation inherent to UWFA imaging technique. The correction function is based on the geometrical eyeball shape, therefore it is fully automated and depends only on pixel distance from the center of the imaged retina. The method’s performance was assessed on a database containing 256 UWFA images with the use of several image quality measures that show the correction method improves image quality. The method is also compared to the commonly used CLAHE approach and was also employed in a pilot study for vascular segmentation, giving a noticeable improvement in segmentation results. Therefore, the method can be used as an image preprocessing step in retinal UWFA image analysis.

The Study of Correction Method for Soil-Water Characteristic Curve of Swelling-Shrinking Soil

2013 ◽  
Vol 712-715 ◽  
pp. 873-876
Author(s):  
Peng Du ◽  
Xiao Ling Liu ◽  
Xiao Ying Li
Keyword(s):  
Soil Water ◽  
Volume Fraction ◽  
Characteristic Curve ◽  
Correction Method ◽  
Matric Suction ◽  
Engineering Properties ◽  
Water Volume ◽  
Volume Deformation ◽  
Water Volume Fraction ◽  
The Relationship

The swelling-shrinking soil embodies the features of expanding when absorbing water and shrinking when drying out; its engineering properties are sensitive to water fluctuation. Mainstream test instruments of SWCC cannot accurately get its relationship between matric suction and water volume fraction. So a correction method based on the results of shrinkage test is carried out. The method is accomplished by using the volume deformation which is obtained in shrinkage test to calculate its real water volume fraction and then combining the results of SWCC test and finally constructing the relationship between matric suction and water volume fraction. Through real application, this method is proved to be feasible and essential.

Hydraulic System Simulation Research of Demolishing Robots Based on Matlab

2013 ◽  
Vol 753-755 ◽  
pp. 2757-2760
Author(s):  
Jing Yan
Keyword(s):  
Hydraulic System ◽  
System Analysis ◽  
Low Cost ◽  
Characteristic Curve ◽  
Response Characteristic ◽  
Analysis Software ◽  
Simulation Research ◽  
Modular Modeling ◽  
Modeling Methods ◽  
Set Up

Modular modeling methods based on the reasonable simplifying and supposing of hydraulic system of demolishing robots are proposed in this paper, dynamic mathematical model of each hydraulic element of demolishing robots is set up by the dynamic system analysis software package Simulink of Matlab, response characteristic curve is obtained by the simulation, and analysis of the simulation results is operated in this paper. The experimental results explicate that the hydraulic system is stably, real-time, low-cost, and easy to expand; it can meet the applying requirements of demolishing robots, and it provides the theory basis for the project applying of the hydraulic system of demolishing robots.

scholarly journals Correction for a measurement artifact of the Multi-Angle Absorption Photometer (MAAP) at high black carbon mass concentration levels

2013 ◽  
Vol 6 (1) ◽  
pp. 81-90 ◽  
Author(s):  
A.-P. Hyvärinen ◽  
V. Vakkari ◽  
L. Laakso ◽  
R. K. Hooda ◽  
V. P. Sharma ◽  
...  
Keyword(s):  
Black Carbon ◽  
Flow Rate ◽  
Accumulation Rate ◽  
Correction Method ◽  
Correction Function ◽  
Carbon Mass ◽  
The Individual ◽  
Measurement Artifact ◽  
Sudden Decrease ◽  
Absorption Photometer

Abstract. The Multi-Angle Absorption Photometer (MAAP) is a widely-used instrument for aerosol black carbon (BC) measurements. In this paper, we show correction methods for an artifact found to affect the instrument accuracy in environments characterized by high black carbon concentrations. The artifact occurs after a filter spot change – as BC mass is accumulated on a fresh filter spot, the attenuation of the light (raw signal) is weaker than anticipated. This causes a sudden decrease, followed by a gradual increase in measured BC concentration. The artifact is present in the data when the BC concentration exceeds ~3 μg m−3 at the typical MAAP flow rate of 16.7 L min−1 or 1 m3 h−1. The artifact is caused by erroneous dark counts in the photodetector measuring the transmitted light, in combination with an instrument internal averaging procedure of the photodetector raw signals. It was found that, in addition to the erroneous temporal response of the data, concentrations higher than 9 μg m−3 (at the flow rate of 16.7 L min−1) are underestimated by the MAAP. The underestimation increases with increasing BC accumulation rate. At a flow rate of 16.7 L min−1 and concentration of about 24 μg m−3 (BC accumulation rate ~0.4 μg min−1), the underestimation is about 30%. There are two ways of overcoming the MAAP artifact. One method is by logging the raw signal of the 165° photomultiplier measuring the reflected light from the filter spot. As this signal is not affected by the artifact, it can be converted to approximately correct absorption and BC values. However, as the typical print formats of the MAAP do not give the reflected signal as an output, a semi-empirical correction method was developed based on laboratory experiments to correct for the results in the post-processing phase. The correction function was applied to three MAAP datasets from Gual Pahari (India), Beijing (China), and Welgegund (South Africa). In Beijing, the results could also be compared against a photoacoustic spectrometer (PAS). The correction improved the quality of all three MAAP datasets substantially, even though the individual instruments operated at different flow rates and in different environments.

scholarly journals Using Evolutionary Computation on GPS Position Correction

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Jung Yi Lin
Keyword(s):  
Evolutionary Computation ◽  
Global Positioning System ◽  
Handheld Devices ◽  
Correction Function ◽  
Gps Receiver ◽  
Correction Algorithm ◽  
Gps Receivers ◽  
Global Positioning ◽  
Position Correction ◽  
Hardware Reconfiguration

More and more devices are equipped with global positioning system (GPS). However, those handheld devices with consumer-grade GPS receivers usually have low accuracy in positioning. A position correction algorithm is therefore useful in this case. In this paper, we proposed an evolutionary computation based technique to generate a correction function by two GPS receivers and a known reference location. Locating one GPS receiver on the known location and combining its longitude and latitude information and exact poisoning information, the proposed technique is capable of evolving a correction function by such. The proposed technique can be implemented and executed on handheld devices without hardware reconfiguration. Experiments are conducted to demonstrate performance of the proposed technique. Positioning error could be significantly reduced from the order of 10 m to the order of 1 m.

scholarly journals Vehicle License Plate Detection and Perspective Rectification

2019 ◽  
Vol 25 (5) ◽  
pp. 47-56 ◽  
Author(s):  
Musaed Alhussein ◽  
Khursheed Aurangzeb ◽  
Syed Irtaza Haider
Keyword(s):  
Correction Method ◽  
Traffic Monitoring ◽  
Character Segmentation ◽  
Outdoor Environment ◽  
License Plate ◽  
Correction Algorithm ◽  
Vehicle Identification ◽  
Corner Points ◽  
Considerable Impact ◽  
License Plate Detection

The character segmentation and perspective rectification of Vehicle License Plate (VLP) is essential in different applications, including traffic monitoring, car parking, stolen vehicle recovery, and toll payment. The character segmentation of the VLP and its horizontal as well as vertical (pan and tilt) correction is a crucial operation. It has considerable impact on the precision of the vehicle identification process. In this work, we investigate an effective framework for the perspective rectification and homography correction of vehicle's images. The captured images of the vehicle could be tilted in vertical or horizontal or vertical-horizontal mix directions due to different movements. For reasonable high identification results, a polynomial fitting based homography correction method for rectifying the tilted VLPs is applied. A method for determining four corner points of the rotated VPLs is explored. These four detected corner points are applied in the homography correction algorithm. For comprehensively evaluating the performance of the proposed framework, the detected VLPs in various directions, such as horizontal, vertical, and mix horizontal-vertical, are rotated. For the experiments, the real images of the vehicles in the outdoor environment, from different directions and different distances are captured. With our proposed method, we achieve an accuracy of 97 % and 95 % for the simulated and real captured images, respectively.

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