Amplitude-preserved common image gathers by wave-equation migration 71st Ann

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基于在轨MTF_测试的定量图像质量提升方法

1 单方向可定量图像质量提升方法
基于在轨 MTF 测试的单方向可定量图像质量提升，主要是指将 TDI 推扫型光学遥感载荷在沿轨或
光学遥感系统 PSF
空域滤波系数
垂轨方向的 MTF 提升到设定值上，并据此设计空域滤波系数实现定量的图像质量提升。空域滤波系数的设计如图 1 所示，其中光学遥感系统的点扩展函
上述研究未引入光学遥感载荷的在轨实际成像特性，本文在空域自适应 MTFC 遥感图像复原算法[16] 的基础上，针对 TDI 推扫型光学遥感载荷在垂轨和沿轨两个方向因不同影响因素导致的差异化退化现象，提出了基于在轨 MTF 测试的单方向可定量图像质量提升方法，通过研究频率增强与空域滤波之间的关系，旨在进一步提升光学遥感相机在轨图像质量，实现针对载荷不同特性的图像质量提升，最后进行遥感图像质量评价，满足不同场景的应用需求。
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航天返回与遥感
2024 年第 45 卷
rail direction is increased by 2.51 times, and the clarity of the obtained image is improved by 8.33%, which proves that the method can effectively achieve quantitative image quality improvement.
收稿日期：2023-11-05 基金项目：国家自然科学基金（42050202）引用格式：周雨荷, 伏瑞敏, 齐文雯. 基于在轨 MTF 测试的定量图像质量提升方法[J]. 航天返回与遥感, 2024, 45(2): 125-133.
ZHOU Yuhe, FU Ruimin, QI Wenwen. Quantitative Image Quality Improvement Method Based on On-Orbit MTF Test[J]. Spacecraft Recovery & Remote Sensing, 2024, 45(2): 125-133. (in Chinese)

MEMS振镜扫描共聚焦图像畸变机理分析及校正

2021年2月Feb. 2021第50卷第2期Vol.50 No.2红外与激光工程Infrared and Laser EngineeringMEMS 振镜扫描共聚焦图像畸变机理分析及校正缪新叫李航锋1,张运海心，王发民込施辛彳(1.中国科学技术大学，安徽合肥230026；2.中国科学院苏州生物医学工程技术研究所江苏省医用光学重点实验室，江苏苏州215163;3.苏州大学附属第二医院，江苏苏州215000)摘要：在皮肤反射式共聚焦显微成像过程中，针对MEMS 振镜二维扫描引起的共聚焦图像畸变，开展了光束偏转理论分析，得出了投影面扫描图像的具体形状表征,理论畸变图像与真实畸变图像一致，明确了畸变机理，提出一种有效的畸变校正算法，实现对图像二维畸变的校正。

首先记录原始光栅畸变图像，然后基于Hessian 矩阵提取光栅中心线，拾取特征点并设置基准参考线，通过基于最小二乘法的7次多项式插值法标定二维方向像素畸变校正量，采用加权平均法填补间隙像素灰度值，最终实现图像畸变校正。

利用网格畸变测试靶实验得出7次多项式插值后的校正决定系数最高、均方根误差值最低，整幅512行图像在7次多项式插值后最优行数占379行，比例为74%,通过残差分析，二维方向上残差最大为4个像素，最小为0个像素，平均为1.15个像素，校正结果较为精确。

皮肤在体实时成像实验显示，图像畸变校正后组织结构特征更加真实准确，表明这种校正算法有效可行，有助于皮肤疾病的准确诊断。

关键词：图像二维畸变；机理分析；Hessian 矩阵；光栅；多项式插值中图分类号：TH742.9文献标志码：A DOI ： 10.3788/IRLA20200206Analysis and correction of image distortion in MEMSgalvanometer scanning confocal systemMiao Xin 12, Li Hangfeng 1, Zhang Yunhai 1,2*, Wang Famin 1,2, Shi Xin 3(1. University of Science and Technology of China, Hefei 230026, China;2. Jiangsu Key Laboratory of Medical Optics, Suzhou Institute of Biomedical Engineering and Technology,Chinese Academy of Sciences, Suzhou 215163, China;3. The Second Affiliated Hospital of Soochow University, Suzhou 215000, China)Abstract: Aiming at the distorted confocal images caused by the two-dimensional scanning of MEMS galvanometer during skin imaging by reflectance confocal microscopy, the theoretical analysis of beam deflectionwas carried out, and the specific shape representation of projection plane scanning image was obtained. It was concluded that the theoretical distortion image was consistent with the real distortion image. The distortionmechanism was clarified and a distortion correction method was proposed. First, the original distorted grating image was recorded, then the center lines of grating were obtained based on the Hessian matrix, after that feature points were picked and datum reference lines were set. Finally, the correction to the distorted confocal images wasrealized by calibrating the corrections of the two-dimensional pixel distortions using polynomial interpolation收稿日期：2020-10-12；修订日期:2020-11-15基金项目:国家重点研发计划(2017YFC0110305)；山东省自然科学基金(ZR2019BF012)；济南市“高校20条”资助项目(2018GXRC018)；苏州市民生科技项目(SS201643)红外与激光工程第50卷第2期based on the least square method and filling the gray value of gap pixels by weighted average method.By the experiment of measuring target with grid distortion,the correction coefficient was the highest and the root mean square error was the lowest after polynomial interpolation of degree7.Also,the optimal number of512rows was 379,accounting for74%.The residual distortions were accurately evaluated,in two dimensional,the maximum value is4pixels,the minimum value was0pixel and the average value was L15pixels,so the results were accurate.The experiment of in vivo real-time skin imaging shows that the organizational structure features are more real and accurate after corrections.So this method is effective and feasible,which is helpful for accurate diagnosis of skin diseases.Key words:two-dimensional distortions of images;polynomial interpolation0引言作为一款新型影像学临床诊断设备，皮肤反射式共聚焦显振镜利用皮肤中血红蛋白、黑色素和角蛋白等不同组织成分的折射率差异进行成像，为皮肤组织的实时观测提供有效的技术手段，在恶性皮肤肿瘤早期诊断、治疗后随访等方面发挥了愈发重要的作用"役为进一步实现皮肤病检查时的便捷性,需要发展手持式皮肤共聚焦显振镜，由于受到系统体积和重量限制，系统中的核心部件扫描振镜要采用单镜面式MEMS振镜实现二维扫描成像,该扫描方式使得采集到的图像存在较为严重的二维畸变，扭曲了皮肤组织真实的结构形态.如不对这种图像畸变进行校正，将不利于医生观察皮损组织真实形态、边界轮廓、结构特征等信息，直接影响临床诊断结果因此，需要在分析产生图像畸变机理的基础之上，实现畸变校正，将真实图像信息准确呈现，为皮肤疾病诊断奠定基础。

基于视觉传达效果的图像压缩感知重建算法研究

文章编号:1007-757X(2021)04-0061-05基于视觉传达效果的图像压缩感知重建算法研究沈凤仙(三江学院计算机科学与工程学院，江苏南京210000)摘要：针对传统的图像压缩感知重建算法的视觉传达效果不好、成像质量低0缺4,将图像分块理论D入压缩感知图像重建，结合曲波变换具有适合表达边缘细节信息和曲线信息的优4,利用曲波变换对MRI图像进行稀疏表示，形成一种基于视觉传达效果的MRI图像压缩感知图像重构算法#选择信噪比、相对"误差和匹配度为评价m标，通过无噪图像、加噪图像、不同采样频率对重构图像质量影响进行3组实验#实验结果表明，图像重构时，在信噪比、相对"误差和匹配度3个评价m 标上，提出的算法GPBDCT均优于SIDCT和PBDCT，同时GPBDCT具有很强的抵抗噪声的能力，在保持图像细节和边缘方面效果很好#关键词：小波变换；曲波变换；压缩感知；正则化参数；采样频率；信噪比中图分类号：TN911.73文献标志码：AStudy on Image Compression Perceptual ReconstructionAlgorithm Based on Visual Communication EffectSHEN Fengxian(School of Computer Science and Engineering,Sanjiang University,Nanjing210000,China)Abstract:Aiming at the shortcomings of traditional image compression perceptual reconstruction algorithm,such as bad visual communicatione f ectandlowimagequality,thetheoryofimageblockisappliedintothereconstructionofcompressedpercep-ualimagesTCombiningtheadvantagesofcurvelettransform,whichissuitableforexpressingedgedetailsandcurveinforma-ion,the MRIimagesarerepresentedsparinglybycurvelettransformTAn MRIimagereconstructionalgorithmbasedonvisual communication effect is proposed.The signal-to-noise ratio,relative—error and matching degree are selected as the evaluation indexes.The results of three groups of experiments show that the quality of reconstructed images is affected by noise-free images,noisy images and different sampling frequencies and PBDCT is superior to SIDCT and PBDCT in SNR,relative—error and matching degree.PBDCT has strong ability to resist noise and is good at preserving image details and edges.Key words:wavelet transform；curvelet transform；compression perception；regularization parameter；sampling frequency%SNR0引言磁共振成像(Magnetic Resonance Imaging,MRI)技术能够提供活体组织的细节图像，同时具有对人体无辐射性伤害等优点，因此被广泛地应用于人脑、胸部、心脏以及人体其他部位结构的成像。

基于多层次并行算法的共成像点道集抽取

ａｄｕｉｇＯｐｎｎｅｅｙｎｄ，ｔｅｅｙｄｖｌｐｎｅｏｅａｉｎｌｐｒｒｎｅｏａｈｎｄｓｎｓｎｅＭＰｉｖｒｏｅｈｒｂｅｅｏｉｇｔｐｒｔａｅｏｍａｃｆｅｃｏｅ．Ｔｈｘｅｍｅｔｌｈｏｆｅｅｐｒｎａｉｒｓｌｈｗａｈｔｏａｅｔｒｐｒｌｌｐｅｕｎａａｌｌｆｃｅｃｉｒｖｓｃｍｐｔｔｎｌｆｃｅｃｆｅｕｔｓｏｔｔｅｍｅｈｄｈｓｂｔａａｌｅｄｐａｄｐｒｌｉｉｎｙ，ｍｐｏｅｏｕａｉａｉｉｎｙｏｓｈｔｅｅｓｅｅｏｅｍｉａｉｎｖｌｃｔｎｌｓｓｒｖｄｓａｂｔｒｐｒｌｌｓｒｔｇｒｓｉｍｉａａｐｏｅｓｎｒｏｇｔｅｏｉａａｙｉ，ｐｏｉｅｅｔａａｌｔｅｆｅｓｃｄｔｒｃｓｉｇ，ａｄｈｍｐｒａｔｉｎｆｙｅｅａｙｏｎａｉｏｔｎｇｉ－ｓｓｉｃｎｅｏｃｕｌｐｏｕｔｎａｃｎａｔａｒｄｃｉ．ｏＫＥＹＷＯＲＤＳ：ＣｕｔｒＭｕｔ —ｌｖｌｐｒｌｌｃｍｐｔｇ；ｒｌｓ；ｌｅｉｅｅａａｌｏｕｉＰｅ—ｓｃｅｔｇａｉｎ；ｏｅｎｔｋｄｐｈｍｉｒｔａｏＣｍｍｏｍａｅｇｔｅｓｎｉｇａｈｒ
明，于多层次并行的共成像点道集抽取具有良好的并行加速比和并行效率，效提高了偏移速度分析的计算效率，震基有为地

转换波波动方程叠前深度偏移

方法，近似于震源子波的数据和检波器所接收到将
的数据，分别延拓至地下。并在需要成像的位置，根据反射产生的原理，演该位置的反射系数。因反
此，动方程类叠前深度偏移主要分为波场延拓和波
过转换波偏移成像弥补纵波存在的缺陷。
关键词：转换波；叠前深度偏移；偏移速度分析中图分类号：Ｐ６１４３．文献标识码：Ａ
波偏移速度分析方法更加精确。近年来针对纵横
０前言
偏移成像技术是地震勘探资料处理中及其重要的一环，结果将直接影响井位的确定。传统的其地震波勘探以纵波为主，偏移成像方法也多集中于纵波，数十年的发展过程中，技术理论也日趋在其
第３卷第２４期
物探化探计算技术
２１年３０２月
文章编号：１（ — １４（０２０ — ０９ — ０（１７９２１）２１８６）］
转换波波动方程叠前深度偏移
刘奇琳
（．１中国石油化工股份有限公司西南分公司博士后科研工作站，成都２中国石油化工股份有限公司西南油气分公司，．成都６０８；１０１６００；１００
对声波方程沿深度方向（向）行单程波ｚ方进
分解，以得到单程波方程：可
３Ｐ
ｄ
其中ｋ为波场的纵向波数，表述为：

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Angle-domaincommonimagegathersbywave-equationmigrationMarieL.Prucha*andBiondoL.Biondi,StanfordUniversity,WilliamW.Symes,RiceUniversity

SUMMARYShot-andoffset-domaincommonimagegathersencounterproblemsincomplexmedia.Theycanplaceeventsthatcomefromdifferentpointsinthesubsurfaceatonesubsurfacelocationbasedonidenti-calarrivaltimesandhorizontalslownesses.Angle-domaincommonimagegathersuniquelydeﬁneraycouplesforeachpointinthesubsur-face,thereforeeacheventinthedatawillbeassociatedwithonlyonesubsurfacelocation.Itispossibletogenerateangle-domaincommonimagegatherswithwave-equationmigrationmethodsandtheseangle-domaincommonimagegathersmaybeusedforvelocityanalysisandamplitude-versus-angleanalysis.INTRODUCTIONCurrentdepthimagingtechnologyworksverywellinareasthathaveslowvelocityvariationsbutmayfailinmorecomplexareas(Claer-bout,1985)foravarietyofreasons,suchasmultiplereﬂections,badvelocities,andspatialaliasing.Onepotentialcauseofimagingfailureisreﬂectorlocationambiguityduetomultipathingofreﬂectedenergy:itispossiblethatasingleeventrecordedinthedataatonesurfacelocationcouldcomefromreﬂectorsattwoormoresubsurfaceloca-tions.Besidescontributingtoimagingartifacts,reﬂectorambiguitycontributesnon-ﬂateventstocommonimagegathers,thusrenderingvelocityanalysisambiguous(NolanandSymes,1996).Severalauthorshavesuggestedangledomainimagingasasolutionforthereﬂectorambiguity(Xuetal.,1998;Brandsberg-Dahletal.,1999).Angledomainsectionscollecttheenergyinadatasetwhichhasscatteredoveraspeciﬁcreﬂection(“opening”)angle.Wewillarguebelowthataneventinananglesectionuniquelydeterminesaraycouple,whichinturnuniquelylocatesthereﬂector.Thusimagingartifactsandvelocityupdateambiguityduetomultipathingareeliminatedinthisdomain.Multipathingisbetterhandledbywave-equationmigrationmethodsthanKirchhoffones,thereforetheformerareanaturalchoiceforpro-ducingangle-domaincommonimagegathers(CIGs).WepresentasimplemethodforextractingCIGsfrom3-DprestackdatadownwardcontinuedusingtheDoubleSquareRootequation(DSR).Themethodisbasedonaslant-stackdecompositionofthedownwardcontinuedwaveﬁeldateachdepthlevel.OurmethodisthusdifferentfromthemethodproposedbyOttoliniandClaerbout(1984),thatappliestheDSRtodownwardcontinueprestackdataslant-stackedatthesurface.Inlayeredmediathetwomethodsshouldproduceequivalentresults,butinpresenceoflateralvelocityvariationsplane-wavedownwardcon-tinuationisnotstrictlyvalidandtrueangle-domainCIGscanonlybeproducedbywaveﬁelddecompositionatdepth.MigrationmethodsbasedonDSRoperatorshavebeenappliedto2-Dprestackmigrationforlongtime(Claerbout,1985).However,thedirectapplicationofDSRmigrationmethodsto3-Dprestackdatahavebeenpreventedbythetremendouscomputationalcost.Onlyrecentlycomputationallyefﬁcientmethodstocontinue3-Dprestackdatahavebeenpresented(BiondiandPalacharla,1996;Mosheretal.,1997).Inparticular,common-azimuthmigrationisanattractivealternativetoKirchhoffmigrationforsub-saltimagingbecauseofitsrobustnesswithrespecttothecomplexmultipathingthatisinducedbysaltbodies.Thisabstractwillexplainhowsomewidelyusedcommonimagegatherscancontainreﬂectorambiguityduetomultipathingandwhyangledomaincommonimagegatherswillnot.Thenwewilldemonstratetheconstructionofangle-domaincommonimagegathersfromwaveequationdownwardcontinueddataforuseinvelocityanalysisandamplitude-versus-reﬂectionangleanalysis.KINEMATICSOFMULTIARRIVALSINTHESHOTANDOFFSETDOMAINS

Thekinematicsofshotdomaincommonimagegathersandoffsetdo-mainimagegathersarewellunderstoodinconstantvelocityandzmedia.Difﬁcultiesarisewhenwebeginconsideringcomplexsub-surfaceswithrapidlateralvelocityvariations.Evenin2-Ditiseasytoconstructamodelforwhichanindividualcommonshotgatherorcommonoffsetgathercancontaintwoeventsfromtwopointsinthesubsurfacethatarriveatthesametimeandareindistinguishable.Letusinvestigateparticularcasesoftheseoccurrences.

Anindividualcommonshotgatherisparameterizedbythereceiverlo-cationr.Iftworaypathsbetweenthesamesourceandreceiverexistsuchthattheyhavethesamereceiverhorizontalslownessprandthetwo-waytraveltimealongeachisthesame,itisimpossibletodistin-guishbetweenthetworeﬂectorlocations(NolanandSymes,1996).Figure1showsaverysimplecaseofthis.

Figure1:Individualshotgather:thecircularlensisalowvelocityanomalysothetraveltimesandprareidentical.

Anindividualcommonoffsetgatherisparameterizedbymidpointm.Supposethatthehorizontalmidpointslownesspmpspristhesamefortworaypathswiththesametraveltimes.Onceagain,thetworaypathsrepresentthesameevent,andthelocationofthereﬂectorcausingthiseventiscompletelyambiguous.Figure2showsacasewhereps1pr1andps2pr2sothatpm1pm20.