基于PDE的閃光照相圖像消噪聲方法研究.pdf

1、Y8U990分類號(hào)T—P391533(1jUDC密級(jí)編號(hào)中國(guó)工程物理研究院學(xué)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(dǎo)教師姓名劉瑞根研究員中請(qǐng)學(xué)位級(jí)別碩十專業(yè)名稱光學(xué)論文提交開(kāi)期2005510論文答辯H期學(xué)位授予單位和日期中國(guó)工程物理研究院答辯委員會(huì)主席評(píng)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