Slides_Chapter19

Chapter19Visualpatternrecognition,PracticalImageandVideoProcessingUsingMATLAB,ByOgeMarquesCopyright2011byJohnWiley(b)thesampleisapoorexampleoftheunderlyingstructureoftheclass.Normalization:featurevectorsmayneedtobenormalizedbeforedistance,similarity,andprobabilitycalculationstakeplace.Insertionofmissingdata:(optional).,ByOgeMarquesCopyright2011byJohnWileyaperfectclassifierwouldshowalloff-diagonalelementsequaltozero.,ByOgeMarquesCopyright2011byJohnWileyfromthatpointonitfallsmonotonicallyuntilthepointwhererecallreachesone.,ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Precisionandrecall,F1:amorecompactrepresentationoftheprecisionandrecallpropertiesofasystem.,ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Precisionandrecall,Example19.4:Animageretrievalsystemproducedthefollowing10rankedresultsforasearchoperationagainstadatabaseof500images,ofwhich5arerelevanttothequery:,ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Precisionandrecall,Example:Recallandprecisionvalues,P-Rgraph,ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Distanceandsimilaritymeasures,ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Distanceandsimilaritymeasures,SimilaritymeasuresVectorinnerproduct:Tanimotometric:,ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Statisticalpatternclassificationtechniques,Sofar,objectspropertiesarerepresentedusingfeaturevectorswhichareprojectedontoafeaturespace.Theresultingpointsinthen-dimensionalfeaturespaceshouldideallybedistributedinawaythatcorrelatesproximityinthefeaturespacewithsimilarityamongtheactualobjects.Inotherwords,featurevectorsassociatedwithobjectsfromthesameclasswillappearclosetogetherasclustersinthefeaturespace.,ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Statisticalpatternclassificationtechniques,Thejobofastatisticalpatternclassificationtechniqueistofindadiscriminationcurve(orahyper-surface,inthecaseofann-dimensionalfeaturespace)thatcantelltheclusters(and,therefore,classes)apart.,ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Statisticalpatternclassificationtechniques,Threemaintechniques:Minimumdistanceclassifierk-nearestneighborsBayesianclassifier,ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Statisticalpatternclassificationtechniques,Minimumdistanceclassifier,ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Statisticalpatternclassificationtechniques,k-nearestneighborsclassifierWorksbycomputingthedistancebetweenanunknownpatternsfeaturevectorandthekclosestpoints(notclasses)toitinthefeaturespace.Itthenassignstheunknownpatterntotheclasstowhichthemajorityoftheksampledpointsbelong.Advantages:simplicity(e.g.,noassumptionsneedtobemadeabouttheprobabilitydistributionsofeachclass)andversatility(e.g.,ithandlesoverlappingclassesorclasseswithcomplexstructurewell).Disadvantages:computationalcost.,ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Statisticalpatternclassificationtechniques,k-nearestneighborsclassifier:example,ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Statisticalpatternclassificationtechniques,BayesianclassifierRationale:aclassificationdecisioncanbemadebasedontheprobabilitydistributionsofthetrainingsamplesforeachclass.Anunknownobjectisassignedtotheclasstowhichitismorelikelytobelongbasedontheobservedfeatures.,ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Hands-on,Tutorial19.1:Featureextractionandrepresentation(page491),ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Tutorial19.1Patternclassification,OCRproblemDataset:1000trainingimages+1000testimages10classes:0,1,2,9KNNclassifier(courtesyoftheSTPRtool)Preprocessing,ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Tutorial19.1Patternclassification,1stattempt:usingeccentricityandEulernumberasfeaturesResults(trainingset)Partialconclusions,ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Tutorial19.1Patternclassification,Results(testset),ByOgeMarquesCopyright2011byJohnWiley&Sons,Inc.Allrightsreserved.,Tutorial19.1Patternclassification,Results(testset),ByOgeMarquesCopyrigh