基于PDE的閃光照相圖像消噪聲方法研究.pdf

1、Y8U990分類號T—P391533(1jUDC密級編號中國工程物理研究院學位論文基于PDE的閃光照相圖像消噪聲方法研究錢僥新指導教師姓名劉瑞根研究員中請學位級別碩十專業(yè)名稱光學論文提交開期2005510論文答辯H期學位授予單位和日期中國工程物理研究院答辯委員會主席評閱人2005年5月10口堊主旦里曼墮旦堂墨塑墮堡塑堂妻塑鎏翌窒AbstraetTheedgesareveryimportantinformationintheXrayima

2、ges，SmoothingXrayimagesshouldbalancetheremovingnoisesagainstpreservingedgesSo，thesmoothinghastobeadaptivelycontrolledwithtwoprinciples：(1)lesssmoothinginthelocationswithimageedges，andmoresmoothinginthelocationswithotherr

3、egions；and(2)minimalsmoothinginthedirectionsacrossimageedgesandmaximalsmoothinginthedirectionsalongimageedgesTheimagedenoisingmethodsbasedonthePartialDifferentialEquations(callPDEforshort)isakindofnonlineardiffusionfilte

4、ringmethodsThemethodsuseanoniineardiffusionwithadirectionaldistributionofcoefficientfunctioninsteadofisotropicdiffusionofGaussianconvolutionThus，themethodcallprotecttheimageedgeswhileeliminatingthenoisesSo，themethodsarea

5、ppropriatetoourtaskInthepapertheSOurCeofthePDE’SmethodsintheimageprocessingisdiscussedinthepaperBysolvingthelinearconductionequation，wecangetthesmoothedresultswhich黜equivalenttotheresultsofGaussianconvolutionThen，wediscu

6、sstheadaptivemechanismofthenonlineardiffusionfiltering，Byselectingtheproperdiffusioncoefficientfunction(alsocalledgestoppingfunction)，thenonlineardiffusionfilteringmethodscancontrolthedifferentdegreeofthediffusioninthedi

7、fferentregionoftheimageThatistosaythediffusionisweakintheedgestoprotecttheedgesandthediffusionisstrongintheflatregiontosmooththenoisesThedifferenteffectsofthedifferentnonlineardiffusionfiltersarealsodiscussedinthepaperWe

8、thenunifyallkindsofdiffusionfilterswithoneformula’Theformulatakesa11factorsinthediffusionproblemhaloaccountTheselectionofallparametersisdiscussedindetailSo，wecarlgettheabsoluteadaptivenonlineardiffusionfilterFurthermore，

9、weproposcanonlineardiffusionfilterwhichisbasedonthedirectionsoftheimageedgesThenewmethodisconstructedontheorthogonalcoordinateoftheimageedgesThedirectionofdiffusionissufficientlyconsideredinthemethodThediffusionisweakint

10、heorthogonaldirectionoftheimageedgestoprotecttheedgesandstrongintheparalleldirectionoftheimageedgestoeliminatethenoisesefficientlyTheadvantageofthenewmethodistoillustratethemechanismofthenonlineardiffusionfilterwithnocom

11、plexanalysisintheoryTherearemanyimpulsenoiseswithlargeamplitudeintheCCD(ChargeCoupledDevice)imagesofflashXrayradiographyItincreasesthedifficultyof0122“taskbecausenonlineardiffusionfilteringisnotefficienttothenoisesTosolv