Decomposition(四分树切割)与相关MATLAB指令简介.ppt

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1、QuadtreeDecomposition(四分樹切割)與相關MATLAB指令簡介李棟良Contents黑白影像的四分樹表示法灰階影像的四分樹表示法MATLABdemo相關MATLAB指令簡介2黑白影像的四分樹表示法給一張黑白影像如圖1所示。利用四分樹的切割方式，可將圖1的影像以樹狀的方式表示成圖2。圖1黑白影像圖2四分樹表示法四分樹切割3灰階影像的四分樹表示法給一張灰階影像，利用四分樹的切割方式，亦可將影像以樹狀的方式來表示。Anoperationthatsubdividesanimageintoblocksthatcontain"similar"

2、pixels.某子影像(block)是否繼續分割是依據該子影像內之graylevel範圍是否超出臨界值(0

3、.qtsetblk-Setblockvaluesinquadtreedecomposition.qtgetblk-Getblockvaluesinquadtreedecomposition.8qtdecompS=qtdecomp(I,threshold)splitsablockifthemaximumvalueoftheblockelementsminustheminimumvalueoftheblockelementsisgreaterthanthreshold.thresholdisspecifiedasavaluebetween0and1.If

4、Iisuint8,thethresholdvalueyousupplyismultipliedby255todeterminetheactualthresholdtouse.9qtdecompS=qtdecomp(I,threshold,mindim)willnotproduceblockssmallerthanmindim,eveniftheresultingblocksdonotmeetthethresholdcondition.10qtdecompS=qtdecomp(I,threshold,[mindimmaxdim])willnotprod

5、uceblockssmallerthanmindimorlargerthanmaxdim.Blockslargerthanmaxdimarespliteveniftheymeetthethresholdcondition.maxdim/mindimmustbeapowerof2.11ViewthequadtreedecompositionofamatrixI=111123661121456811117777111166552022202212342022222054782022202091240122022202013141516S=qtdecomp

6、(I,5);disp(full(S));400020200000000000002020000000004000202000000000000020110000001112Findthelocationsofall4x4blocksinthequadtreedecomposition>>SS=(1,1)4(5,1)4(1,5)2(3,5)2(5,5)2(7,5)2(1,7)2(3,7)2(5,7)2(7,7)1(8,7)1(7,8)1(8,8)1>>[i,j]=find(S==4)i=15j=1113