冈萨版-数字图像处理-双语课程-复习PPT.ppt

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1、Duetoprocessing,storage,andsamplinghardwareconsiderations,thenumberofgraylevelstypicallyisanintegerpowerof2:L=2k,kiscalledthebitdepth.Storagerequirementcalculation:Thenumberofbits,b,requiredtostoreadigitizedimageis:b=M×N×kWhenM=N,thisequationbecomes:b

2、=N2kTherequirementofthegraylevelvalueLAsetofpixelsallofwhichare4-connectedtoeachotheriscalleda4-component;ifallthepixelsare8-connectedthesetisan8-component.4-component4-componentOnlyone8-componentbuttwo4-component8-componentIllustrationofdifferentconn

3、ectedcomponents1.TheEuclideandistancebetweenpandqisdefinedas:DifferentwaysofmeasuringdistanceUsingthismethod,thepixelshavingadistancelessthanorequaltosomevaluerfrom(x,y)arethepointscontainedinadiskofradiusrcenteredat(x,y).pq2.TheD4distance(alsocalledc

4、ityblockdistance)betweenpandqisdefinedas:Usingthismethod,thepixelshavingaD4distancefrom(x,y)lessthanorequaltosomevaluerformadiamondcenteredat(x,y).Forexample,thepixelswithD4distance≤2from(x,y)formthefollowingcontoursofconstantdistance:ThepixelswithD4=

5、1arethe4-neighborsof(x,y).2211221022212D4distanceDifferentwaysofmeasuringdistancecon’t3.TheD8distance(alsocalledchessboarddistance)betweenpandqisdefinedas:D8(p,q)=max(x-s,y-t)2222221112210122111222222D8distanceDifferentwaysofmeasuringdistancecon’tThep

6、ixelswithD8=1arethe8-neighborsof(x,y).p2pp1p4p3Assumethatp,p2,andp4havevalue1andthatp1andp3canhaveavalue0or1.ForV={1},solveforDmdistancebetweenpandp4.Solution:Ifp1andp3are0,thenDmis2.Ifp1is1,p3are0,thenDmbecomes3.Similarly,ifp3is1andp1is0,Dmalsois3.Fi

7、nally,ifbothp1andp3are1,Dmis4.ExampletoillustratefindingDmdistanceContraststretching(对比拉伸)Thresholding(二值化)Transformationfunctions=T(r)CharacteristicsofGray-leveltransformationfunctionsSdependsononlyonepixelvaluerforcalculation.Thisiscalled“pointproce

8、ssing”Illustrationofhistogramequalization4x4imageGrayscale=[0,9]histogram0112233445566789No.ofpixelsGraylevel233242433235242491609sx9No.ofpixelsGrayLevel(j)99998.486.163.330000161616161511600000145600876543210PerformhistogramequalizationOut