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IIR TRANSFER-FUNCTION DESIGN WITH A DOUBLE-OBJECTIVE DIFFERENTIAL correction algorithm

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS 1991年第7期38卷 791-796页

作者： CORTELAZZO, G DESIMONE, C MIAN, GA Dept. of Electron. & Inf. Padova Univ. Italy Department of Electronics and Informatics Universita Degli Studi di Padova Padova Italy

This work proposes an extension of the differential correction algorithm for simultaneous design of real and imaginary part of IIR transfer functions in minimax norm. The method enjoys global convergence and it can be proven to deliver stable IIR filters. Practical implementations of the algorithm compare very favorably with existing design tools. Actual operation is examined by means of filter design examples.

关键词： Minimax algorithms filter design differential correction Butyl rubber correction algorithm iterative solution TRANSFER FUNCTIONS design tools

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An automatic atmospheric correction algorithm for visible/NIR imagery

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INTERNATIONAL JOURNAL OF REMOTE SENSING 2006年第9-10期27卷 2077-2085页

作者： Richter, R Schläpfer, D Müller, A DLR German Aerosp Ctr Remote Sensing Data Ctr D-82234 Wessling Germany Univ Zurich Remote Sensing Labs CH-8057 Zurich Switzerland

The automatic correction of atmospheric effects currently requires visible to short-wave spectral bands (400-2500 nm) to derive high accuracy surface reflectance data. Common techniques employ spectral correlations of dark targets in the short-wave infrared (SWIR, around 2.2 mu m), blue (480 nm) and red (660nm) regions to derive the aerosol optical depth. A large number of current Earth-observing satellite sensors have only three or four spectral channels in the visible and near-infrared (VNIR) region (400-1000 nm), making an automatic image-based atmospheric correction very difficult. This contribution presents a new algorithm and first results with VNIR imagery. The method starts with the assumption of average clear atmospheric conditions (aerosol optical depth AOD=0.27, corresponding to a visibility of 23km) and calculates the surface reflectance in the red and near-infrared (NIR) bands. The second step derives a mask of dark vegetation pixels. It is calculated using multiple thresholds of vegetation index combined with red and NIR surface reflectance values. Then the red band surface reflectance for the dark pixels is estimated from the NIR reflectance as rho(red)=0.1 rho(nir), from which the aerosol optical depth (or visibility) can be calculated. The core of the VNIR algorithm consists of two subsequent iteration loops (visibility and Pred) to improve the visibility estimate. Results of the VNIR method are presented for Landsat-5 Thematic Mapper (TM) and Landsat-7 Enhanced Thematic Mapper Plus (ETM +) imagery using only the first four bands. The performance of the method is compared to the established dark pixel technique where the SWIR bands are included. Results show that the deviation between both methods is usually less than 0.005 reflectance units if measured in terms of the scene-average reflectance, indicating a useful potential for this approach.

关键词： Vegetation Index surface reflectance atmospheric correction thematic mapper correction algorithm VNIR visibility optical thickness

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Topographic correction algorithm for remotely sensed data accounting for indirect irradiance

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INTERNATIONAL JOURNAL OF REMOTE SENSING 2011年第7期32卷 1807-1824页

作者： Zhang, Wanchang Gao, Yongnian Nanjing Univ Ctr Hydrosci Res Nanjing 210093 Peoples R China Chinese Acad Sci Nanjing Inst Geog & Limnol Nanjing 210008 Peoples R China Nanjing Univ Int Inst Earth Syst Sci ESSI Nanjing 210093 Peoples R China

The solar irradiance incidents upon terrain surface are composed of three parts, i.e. direct solar irradiance, diffuse sky irradiance and reflected irradiance from the adjacent surface, respectively. Most of the topographic correction models only account for the topographic effect induced from direct solar irradiance, and few models take the topographic effects from the last two components of solar irradiance into account. A physically based topographic correction algorithm aiming to overcome this shortcoming, called a three-factor correction model, was developed based on theoretical analysis of radiation transferring processes along an undulating surface, atmosphere and satellite sensor geometry under the assumption of Lambertian surface. On the basis of this three-factor correction model, an advanced algorithm accounting for the bidirectional reflectance distribution function (BRDF) nature of non-Lambertian surface, called the three-factor+C topographic correction model, was developed by introducing an empirical parameter C to approximate the indirect irradiance contribution of non-Lambertian surface. Performances of these two newly developed algorithms were tested and compared with those of Cosine and C correction algorithms for a selected rugged terrain on the south flank of the Qinling Mountain, China. Visual comparison and statistical analysis were adopted for quantitative evaluation on topographic corrections of a Landsat-7 Enhanced Thematic Mapper Plus (ETM+) image in the study. The results suggested that the general performance of the algorithms for topographic correction ranks the three-factor+C correction, C correction, three-factor correction and Cosine correction from excellent to poor in order, which implies the promising potential of the proposed algorithms in effective topographic correction applications in remote sensing techniques.

关键词： correction algorithm remote-sensing data irradiance Lambert surface topographic correction algorithms Solar Irradiance Topographic Effects Cosine TWO-COMPONENT

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SENSITIVITY OF AN ATMOSPHERIC correction algorithm FOR NON-LAMBERTIAN VEGETATION SURFACES TO ATMOSPHERIC PARAMETERS

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 1989年第3期27卷 326-331页

作者： GRATZKI, A GERSTL, SAW UNIV CALIF LOS ALAMOS NATL LAB DIV THEORETLOS ALAMOSNM 87545

An atmospheric correction algorithm has been proposed by S.A.W. Gerstl and C. Simmer (1986) that removes atmospheric perturbations from off-nadir radiances measured at the top of the atmosphere in the visible and near-infrared wavelength regions. The correction formalism requires as minimum information the total optical depth of the atmosphere and the surface albedo. The sensitivity of the model to assumptions about the aerosol scattering phase function, the single scattering albedo, and the vertical profile of the optical depth are tested. The authors find that the forward scattering asymmetry must be known most accurately to perform a reliable atmospheric correction for aerosol-laden atmospheres when high-resolution and off-nadir imagery is considered and the surface bidirectional reflectance distribution function is to be retrieved.

关键词： correction algorithm single scattering atmosphere optical thickness Surfaces simmer atmospheric correction Distribution function

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Evaluation of energy correction algorithm for signals of PET in heavy-ion cancer therapy device

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NUCLEAR ENGINEERING AND TECHNOLOGY 2020年第1期52卷 101-108页

作者： Niu, Xiaoyang Yan, Junwei Wang, Xiaohui Yang, Haibo Ke, Lingyun Chen, Jinda Du, Chengming Zhang, Xiuling Zhao, Chengxin Kong, Jie Su, Hong Chinese Acad Sci Inst Modern Phys Lanzhou 730000 Peoples R China Univ Chinese Acad Sci Sch Nucl Sci & Technol Beijing 100049 Peoples R China Chinese Acad Sci Shenzhen Inst Adv Technol Shenzhen 518055 Peoples R China

In order to solve the contradiction between requirements of high sampling rate for acquiring accurate energy information of pulses and large amount of data to be processed timely, the method with an algorithm to correct errors caused by reducing the sampling rate is normally used in front-end read-out system, which is conductive to extract accurate energy information from digitized waveform of pulse. The functions and effects of algorithms, which mainly include polynomial fitting with different fitting times, double exponential function fitting under different sampling modes, and integral area algorithm, are analyzed and evaluated, and some meaningful results is presented in this paper. The algorithm described in the paper has been used preliminarily in a prototype system of Positron Emission Tomography (PET) for heavy-ion cancer therapy facility. (C) 2019 Korean Nuclear Society, Published by Elsevier Korea LLC.

关键词： Positron emission tomography correction algorithm Energy extraction

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Linear CCD Pixel-Response Non-Uniformity correction algorithm

Linear CCD Pixel-Response Non-Uniformity Correction Algorith...

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6th International Symposium on Advanced Optical Manufacturing and Testing Technologies (AOMATT) - Optoelectronic Materials and Devices for Sensing, Imaging, and Solar Energy

作者： Lei, Ning Li, Chunmei Wang, Kun Li, Tao Beijing Inst Space Mech & Elect Beijing 100076 Peoples R China

ISBN: (纸本)9780819491015

The non-uniformity correction of linear Charge-Coupled Devices (CCD) remote camera is essential to gain high quality image. In this paper, a novel Pixel-Response Non-Uniformity (PRNU) correction algorithm is proposed. The disadvantages of traditional correction algorithm, which is the output of dark pixel does not really reflect the current dark current when CCD is partial saturation, is overcome. Secondly, the flat fielding algorithm is improved. The correction algorithm is divided into two independent components based on the mechanism of PRNU, which are dark current noise and its non-uniformity and photoelectricity non-uniformity. Finally, the digital gain function is introduced. The experimental results show that the proposed algorithm can eliminate the image degradation caused by dark current noise and its non-uniformity and photoelectricity non-uniformity. The performance of imaging system is improved.

关键词： CCD correction algorithm image degradation Pixel-Response Non-Uniformity

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Theoretical Analysis and Simulation of Phase Difference correction algorithm

Theoretical Analysis and Simulation of Phase Difference Corr...

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IEEE International Conference on Power and Renewable Energy (ICPRE)

作者： Pan, Feng Song, Qiang Lin, Guoying Li, Linglong Guangdong Power Grid Corp Elect Power Res Inst Guangzhou Guangdong Peoples R China Huazhong Univ Sci & Technol Sch Elect & Elect Engn Wuhan Peoples R China

ISBN: (纸本)9781509030682

The paper presents a discrete spectrum analyzing method based on DFT, which can effectively reduce the phase error by choosing the window function with a real even function that has the linear phase spectrum. Since the traditional DFT algorithm could result in larger measurement error because of the spectral leakage and fence effect, the phase difference correction algorithm is proposed to cope with the problem. The simulation results indicate that the correction algorithm with Hanning window function can effectively improve the metering precision.

关键词： phase difference correction algorithm window function frequency fluctuation DFT

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Extraction algorithm for the Characteristics of the Microwave Connector with correction algorithm

Extraction Algorithm for the Characteristics of the Microwav...

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Asia-Pacific Microwave Conference (APMC)

作者： Shin, Yunsang Nam, Sangwook Seoul Natl Univ Sch Elect Engn Seoul South Korea Seoul Natl Univ INMC Seoul South Korea

ISBN: (纸本)9784902339567

This paper introduces an algorithm that accurately extracts the characteristics of the microwave connector. The characteristics of the microwave connector can be extracted by measuring the thru 1 and thru 2 structure. The thru 1 structure is one in which two connector structures face each other. The thru 2 structure is one that has the known line which assumes that the characteristics are obtained by calculation. The characteristics of the connector structure were accurately extracted by applying T model of the thru 1 and thru 2 structures to the proposed algorithm in the 0.1-18 GHz range.

关键词： characterization algorithm correction algorithm microwave connector microwave measurement

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A novel image-based motion correction algorithm on ultrasonic image 9

A novel image-based motion correction algorithm on ultrasoni...

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9th International Symposium on Multispectral Image Processing and Pattern Recognition (MIPPR) - Parallel Processing of Images and Optimization;and Medical Imaging Processing

作者： Wang, Xuan Li, Yaqin Li, Shigao Wuhan Polytech Univ Coll Hlth Sci & Nursing Wuhan Peoples R China Wuhan Polytech Univ Sch Math & Comp Sci Wuhan Peoples R China

ISBN: (纸本)9781510600553

Lung respiratory movement can cause errors in the operation of image navigation surgery and they are the main errors in the navigation system. To solve this problem, the image-based motion correction strategy should be proposed to quickly correct the respiratory motion in the image sequence. So, the commercial ultrasound machine can display contrast and tissue images simultaneously. In the paper, a convenient, simple and easy-to-use breathing model whose precision was close to the sub-voxel was proposed. The first, in the clinical case the low gray-level variation in the tissue images, motion parameters were first calculated according to the actual lung movement information of each point the tissue images are registered by using template matching with sum of absolute differences metric. Finally, the similar images are selected by a double-selection method which requires global and local threshold setting. The generic breathing model was constructed based on all the sample data. The results of experiments show the algorithm can reduce the original errors caused by breath movement heavily.

关键词： Breath movement correction algorithm ultrasonic image

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TDI CCD Non-Uniformity correction algorithm

TDI CCD Non-Uniformity Correction Algorithm

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4th IEEE Conference on Industrial Electronics and Applications

作者： Li, Tao He, Mingyi Lei, Ning Li, Chunmei Wang, Qingyuan Northwestern Polytech Univ Sch Elect & Informat Xian 710072 Peoples R China Beijing Inst Space Mech & Elect Beijing Peoples R China

ISBN: (纸本)9781424427994

With the increasing demand for the development of high quality remote sensing image techniques, the problem of image degradation causing by pixel-response non-uniformity (PRNU) is becoming a key issue. In this paper, a novel PRNU correction algorithm is proposed and implemented on FPGA hardware platform. Firstly, the characteristic of the CCD noise is analyzed. Secondly, the degradation model of pixel-response non-uniformity is described and the correction algorithm is designed. Thirdly, the calculation precision is analyzed and the factors affecting the result of correction are analyzed. Finally, the proposed correction algorithm is tested in the hardware circuit. The experimental results show that SNR of the image is improved remarkably through correction processing.

关键词： CCD SNR pixel-response non-uniformity correction algorithm

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