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RETRACTED: Evaluation of modulation transfer function of optical lens system by support vector regression methodologies - A comparative study (Retracted article. See vol. 88, pg. 265, 2018)

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INFRARED PHYSICS & TECHNOLOGY 2014年 65卷 94-102页

作者： Petkovic, Dalibor Shamshirband, Shahaboddin Saboohi, Hadi Ang, Tan Fong Anuar, Nor Badrul Rahman, Zulkanain Abdul Pavlovic, Nenad T. Univ Nis Fac Mech Engn Deparment Mech & Control Nish 18000 Serbia Islamic Azad Univ Dept Comp Sci Chalous Branch Mazandaran Iran Univ Malaya Dept Informat Syst Fac Comp Sci & Informat Kuala Lumpur 50603 Malaysia Univ Malaya Dept Comp Syst & Technol Fac Comp Sci & Informat Kuala Lumpur 50603 Malaysia Univ Malaya Dept Hist Fac Arts & Social Sci Bldg Kuala Lumpur 50603 Malaysia

The quantitative assessment of image quality is an important consideration in any type of imaging system. The modulation transfer function (MTF) is a graphical description of the sharpness and contrast of an imaging system or of its individual components. The MTF is also known and spatial frequency response. The MTF curve has different meanings according to the corresponding frequency. The MTF of an optical system specifies the contrast transmitted by the system as a function of image size, and is determined by the inherent optical properties of the system. In this study, the polynomial and radial basis function (RBF) are applied as the kernel function of Support Vector Regression (SVR) to estimate and predict estimate MTF value of the actual optical system according to experimental tests. Instead of minimizing the observed training error, SVR_poly and SVR_rbf attempt to minimize the generalization error bound so as to achieve generalized performance. The experimental results show that an improvement in predictive accuracy and capability of generalization can be achieved by the SVR_rbf approach in compare to SVR_poly soft computing methodology. (C) 2014 Elsevier B.V. All rights reserved.

关键词： modulation transfer function Optical system Image quality Support vector regression Soft computing

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Modified slanted-edge method and multidirectional modulation transfer function estimation

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OPTICS EXPRESS 2014年第5期22卷 6040-6046页

作者： Masaoka, Kenichiro Yamashita, Takayuki Nishida, Yukihiro Sugawara, Masayuki NHK Sci & Technol Res Labs Tokyo 1578510 Japan

The slanted-edge method specified in ISO Standard 12233, which measures the modulation transfer function (MTF) by analyzing an image of a slightly slanted knife-edge target, is not robust against noise because it takes the derivative of each data line in the edge-angle estimation. We propose here a modified method that estimates the edge angle by fitting a two-dimensional function to the image data. The method has a higher accuracy, precision, and robustness against noise than the ISO 12233 method and is applicable to any arbitrary pixel array, enabling a multidirectional MTF estimate in a single measurement of a starburst image. (C)2014 Optical Society of America

关键词： Digital imaging Discrete Fourier transforms Frequency measurement Image resolution modulation techniques modulation transfer function

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RETRACTED: Adaptive neuro-fuzzy prediction of modulation transfer function of optical lens system (Retracted article. See vol.87, pg.153, 2017)

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INFRARED PHYSICS & TECHNOLOGY 2014年 65卷 54-60页

作者： Petkovic, Dalibor Shamshirband, Shahaboddin Anuar, Nor Badrul Nasir, Mohd Hairul Nizam Md Pavlovic, Nenad T. Akib, Shatirah Univ Nis Fac Mech Engn Dept Mech & Control Nish 18000 Serbia Islamic Azad Univ Dept Comp Sci Chalous Branch Chalous 46615397 Mazandaran Iran Univ Malaya Fac Comp Sci & Informat Technol Dept Software Engn Kuala Lumpur 50603 Malaysia Univ Malaya Dept Civil Engn Fac Engn Kuala Lumpur 50603 Malaysia

The quantitative assessment of image quality is an important consideration in any type of imaging system. The modulation transfer function (MTF) is a graphical description of the sharpness and contrast of an imaging system or of its individual components. The MTF is also known and spatial frequency response. The MTF curve has different meanings according to the corresponding frequency. The MTF of an optical system specifies the contrast transmitted by the system as a function of image size, and is determined by the inherent optical properties of the system. In this study, the adaptive neuro-fuzzy (ANFIS) estimator is designed and adapted to predict MTF value of the actual optical system. Neural network in ANFIS adjusts parameters of membership function in the fuzzy logic of the fuzzy inference system. The back propagation learning algorithm is used for training this network. This intelligent estimator is implemented using MATLAB/Simulink and the performances are investigated. The simulation results presented in this paper show the effectiveness of the developed method. (C) 2014 Elsevier B.V. All rights reserved.

关键词： modulation transfer function Spatial frequency Optical system Neuro-fuzzy ANFIS

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Robust Voice Activity Detection Based on Concept of modulation transfer function in Noisy Reverberant Environments 9

Robust Voice Activity Detection Based on Concept of Modulati...

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9th International Symposium on Chinese Spoken Language Processing (ISCSLP)

作者： Morita, Shota Unoki, Masashi Lu, Xugang Akagi, Masato Japan Adv Inst Sci & Technol Sch Informat Sci Nomi Ishikawa Japan Natl Inst Informat & Commun Technol Univ Commun Res Inst Tokyo Japan

ISBN: (纸本)9781479942190

Most of the current voice activity detection (VAD) algorithms deal with clean (noiseless) speech or speech with additive noise conditions. They cannot work in noisy reverberant environments or work poorly if they do, because speech is smeared due to the effects of noise and reverberation. This paper proposes a robust VAD algorithm for precisely detecting speech and non- speech periods in noisy reverberant environments. The proposed VAD algorithm consists of three blocks. The rst block is an estimation of the signal to noise ratio (SNR) which is used to mitigate the additive noise effect on the speech power envelope. The second block is a speech power envelope dereverberation based on the modulation transfer function concept. The last block is a threshold processing on the dereverberated speech power envelope for speech/non-speech decision. Experiments on VAD in both arti cial and realistic noisy reverberant environments revealed that the proposed VAD algorithm significantly outperforms the conventional VAD algorithms.

关键词： Voice activity detection modulation transfer function noisy reverberant environment signal to noise ratio estimation power envelope restoration

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Techniques for measuring comparable lab and field modulation transfer functions

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OPTICAL ENGINEERING 2024年第10期63卷

作者： Rubis, Jordan Leslie, Patrick Meier, Jeffrey Jacobs, Eddie Driggers, Ronald Univ Arizona Wyant Coll Opt Sci Infrared Syst Grp Tucson AZ 85721 USA US Army Redstone Test Ctr Redstone Arsenal AL USA Univ Memphis Elect Engn Memphis TN USA

modulation transfer functions (MTFs) describe how a sensor system transfers spatial frequencies of a scene through an imaging system. For infrared systems, lab measurements are performed in a laboratory setting with a collimated source and a tilted edge target. This method is the standard way to measure a sensor's performance metric. When these sensors are used for practical applications in the field, factors such as focus, atmospheric turbulence, and path radiance limit the performance of the system. These environmentally induced blurs need to be considered when designing sensor systems to ensure the required performance is met. The effects of these factors on the sensor's performance can be quantified by measuring an MTF while in the field. By matching laboratory and static field MTFs, the effects of other blurs can be isolated, such as platform dynamics, vibration, and atmospheric turbulence, which will affect the performance of the system. To obtain a field MTF that matches one measured in the laboratory, the variable field conditions need to be well controlled. The effects of MTF target nonuniformity, tilt angle, illumination spectra, integration time, dynamic range, and number of pixels on target were explored as possible environmental factors affecting the quality of field MTF measurements.

关键词： infrared sensors performance modeling sensor performance modulation transfer function

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modulation transfer function of a modified spatially modulated imaging interferometer

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JOURNAL OF MODERN OPTICS 2013年第20期60卷 1750-1759页

作者： Ai, Jingjing Zhang, Chunmin Gao, Peng Jia, Chenling Xi An Jiao Tong Univ Sch Sci Xian 710049 Peoples R China Minist Educ Key Lab Nonequilibrium Condensed Matter & Quantum Engn La Xian 710049 Peoples R China

The modulation transfer function (MTF) is one of the main criteria for judging the image quality of an imaging system. Together with the well-known optical transfer function, the MTF can be regarded as an objective basis reflecting the comprehensive performance of an imaging interferometer. In order to improve the imaging quality of a modified spatially modulated imaging interferometer (MSMII) with large optical path difference, the boundary conditions of an incident ray, at full field of view, along the x and y directions, respectively, are first calculated by the method of prism expansion, and then the exact expression of the pupil function of the MSMII is given. The two-dimensional MTF of the MSMII is obtained by the Fourier transform. Compared with previous studies, this work gives the two-dimensional MTF for the MSMII, and analyzes the effects of various parameters on the MTF. The optimal values of the incident angle i together with the acute angels beta(1) and beta(2) are chosen as i = 0 degrees and beta(1) = beta(2) = 45 degrees, respectively. If so, a high MTF is obtained, i.e. the imaging quality of the MSMII can satisfy the need of detecting upper atmospheric wind fields.

关键词： modulation transfer function modified spatially modulated imaging interferometer

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modulation transfer function of QWIP and superlattice focal plane arrays

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INFRARED PHYSICS & TECHNOLOGY 2013年 59卷 64-71页

作者： Gunapala, S. D. Rafol, S. B. Ting, D. Z. Soibel, A. Liu, J. K. Khoshakhlagh, A. Keo, S. A. Mumolo, J. M. Nguyen, J. CALTECH Jet Prop Lab Ctr Infrared Sensors Pasadena CA 91109 USA

modulation transfer function (MTF) is the ability of an imaging system to faithfully image a given object. The MTF of an imaging system quantifies the ability of the system to resolve or transfer spatial frequencies. In this paper we will discuss the detail MTF measurements of a 1024 x 1024 pixel multi-band quantum well infrared photodetector and 320 x 256 pixel long-wavelength InAs/GaSb superlattice infrared focal plane arrays. (c) 2013 Elsevier B.V. All rights reserved.

关键词： QWIPs Superlattices Focal Plane Arrays modulation transfer function

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Comparison of ocular modulation transfer function determined by a ray-tracing aberrometer and a double-pass system in early cataract patients

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Chinese Medical Journal 2014年第19期127卷 3454-3458页

作者： Qiao Liya Wan Xiuhua Cai Xiaogu Balamurali Vasudevan Xiong Ying Tan Jiaxuan Guan Zheng David A Atchison Wang Ningli Beijing Tongren Eye Center Beijing Tongren Hospital CapitalMedical University Beijing Ophthalmology & Visual Science KeyLaboratory Capital Medical University Beijing 100730 China College of Optometry Midwestem University Glendale ArizonaUnited States School of Optometry & Vision Science and Institute of Health&Biomedical Innovation Queensland University of TechnologyAustralia

Background The evaluation of retinal image quality in cataract eyes has gained importance and the clinical modulation transfer functions （MTF） can obtained by aberrometer and double pass （DP） system. This study aimed to compare MTF derived from a ray tracing aberrometer and a DP system in early cataractous and normal eyes. Methods There were 128 subjects with 61 control eyes and 67 eyes with early cataract defined according to the Lens Opacities Classification System II1. A laser ray-tracing wavefront aberrometer （iTrace） and a double pass （DP） system （OQAS） assessed ocular MTF for 6.0 mm pupil diameters following dilation. Areas under the MTF （AUMTF） and their correlations were analyzed. Stepwise multiple regression analysis assessed factors affecting the differences between iTrace- and OQAS-derived AUMTF for the early cataract group. Results For both early cataract and control groups, iTrace-derived MTFs were higher than OQAS-derived MTFs across a range of spatial frequencies （P 〈0.01）. No significant difference between the two groups occurred for iTrace-derived AUMTF, but the early cataract group had significantly smaller OQAS-derived AUMTF than did the control group （P 〈0.01）. AUMTF determined from both the techniques demonstrated significant correlations with nuclear opacities, higher-order aberrations （HOAs）, visual acuity, and contrast sensitivity functions, while the OQAS-derived AUMTF also demonstrated significant correlations with age and cortical opacity grade. The factors significantly affecting the difference between iTrace and OQAS AUMTF were root-mean-squared HOAs （standardized beta coefficient=-0.63, P 〈0.01） and age （standardized beta coefficient=0.26, P 〈0.01）. Conclusions MTFs determined from a iTrace and a DP system （OQAS） differ significantly in early cataractous and normal subjects. Correlations with visual performance were higher for the DP system. OQAS-derived MTF may be useful as an indicator of visual performance in early cataract eyes.

关键词： cataract contrast sensitivity function double-pass system modulation transfer function retinal image quality,＂ wavefront aberration

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modulation transfer function of spatially variant sampling retina-like sensor

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OPTIK 2013年第12期124卷 1342-1345页

作者： Wang, Fan Cao, Fengmei Bai, Tingzhu Beijing Inst Technol Sch Optoelect Minist Educ China Key Lab Photoelect Imaging Technol & Syst Beijing 100081 Peoples R China

Space-variant sensors are of great importance in both machine and biological vision, and they have superior imaging property than the rectilinear sensors during high-speed forward motion. We focus on the modulation transfer function (MTF) of a particular spatially variant sampling retina-like sensor, pixels of which are arranged in a log-polar fashion. The 3D MTF of the sensor has been built using Hankel Transformation (HT) based on sampling and imaging property of the sensor. Moreover, the output image is simulated in the light of MTF. This research helps to model the imaging process of an imaging system containing retina-like sensor. (C) 2012 Elsevier GmbH. All rights reserved.

关键词： Retina-like sensor Sampling property Frequency analysis modulation transfer function

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modulation transfer function Measurement System at Different Contrasts for CCD Camera

Modulation Transfer Function Measurement System at Different...

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International Conference on Measurement, Instrumentation and Automation (ICMIA 2012)

作者： Li, Wenjuan Liang, Chuan Jin, Ningzhi Zhou, Meilan Harbin Univ Sci & Technol Sch Elect & Elect Engn Harbin Peoples R China

ISBN: (纸本)9783037855461

In order to achieve MTFs at different contrasts, the MTF measurement system is designed and developed. Two integrating spheres are used to illuminate the face and back of the test target uniformly. The target luminance and background luminance of the test target are regulated by adjusting the attenuators near the entrance of each integrating sphere. The many groups' experimental results indicate that the luminance differences between the values by the system and those by L88 first level luminance meter, which is checked by National Institute of Metrology P. R. China, are within +/- 0.3 cd/m(2). Thereby the measurement precision can be ensured in MTF test. MTFs of Sony camera and Cannon camera at different contrasts are measured by this system. The measurement values show that MTFs at different contrasts can demonstrate the imaging quality fully and objectively. This study provides an effective method to evaluate the imaging quality of visible imaging systems.

关键词： modulation transfer function contrast imaging quality CCD camera

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