《点扩散函数》ppt课件

《《点扩散函数》ppt课件》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、Course15:ComputationalPhotographyCourse15:ComputationalPhotographyA.3:UnderstandingFilm-likePhotographyTumblinJackTumblinNorthwesternUniversityA3:UnderstandingFilm-LikePhotographyor‘from2DPixelsto4DRays’(10minutes)ComputationalPhotographyComputationalPhotographyNaïve,IdealFilm-li

2、kePhotographyAngle(,)Position(x,y)2DSensor:PixelGrid,Film,…Well-Lit3DScene:‘CenterofProjection’Sensor:afilmemulsion,:oragridoflightmeters(pixels)RayRaysandthe‘ThinLensLaw’Focallengthf:whereparallelraysconvergeFocusatinfinity:AdjustforS2=fCloserFocus?LargerS2TryitLive!Physlets…

3、http://webphysics.davidson.edu/Applets/Optics/intro.htmlThinLensfS2SensorRaysandthe‘ThinLensLaw’Focallengthf:whereparallelraysconvergeFocusatinfinity:AdjustforS2=fCloserFocus?LargerS2TryitLive!Physlets…http://webphysics.davidson.edu/Applets/Optics/intro.htmlSceneThinLensfS2fS2Sens

4、orNotOneRay,butaBundleofRaysBUTRaymodelisn’tperfect:ignoresdiffractionLens,aperturesetthepoint-spread-function(PSF)(How?See:Goodman,J.W.‘AnIntroductiontoFourierOptics’1968)SceneSensorApertureLensBasicRayOptics:LensApertureForthesamefocallength:LargerlensGathersawiderraybundle:More

5、light:brighterimageNarrowerdepth-of-focusSmallerlensdimmerimagefocusbecomeslesscriticalmoredepthoffocusFilm-likeOptics:ThinLensFlawsAberrations:Reallensesdon’tconvergeraysperfectlySpherical:edgerayscenterraysComa:diagonalraysfocusdeeperatedgehttp://www.nationmaster.com/encycloped

6、ia/Lens-(optics)LensFlaws:ChromaticAberrationDispersion:wavelength-dependentrefractiveindex(enablesprismtospreadwhitelightbeamintorainbow)Modifiesray-bendingandlensfocallength:f()colorfringesnearedgesofimageCorrections:add‘doublet’lensofflintglass,etc.http://www.swgc.mun.ca/physi

7、cs/physlets/opticalbench.htmlChromaticAberrationLensDesignFix:Multi-elementlensesComplex,expensive,manytradeoffs!ComputedFix:GeometricwarpforR,G,B.NearLensCenterNearLensOuterEdgeRadialDistortion(e.g.‘Barrel’and‘pin-cushion’)straightlinescurvearoundtheimagecenterVignetteEffectsBr

8、ightatcenter,darkatedges.Several