搜索
Unit10DigitalMultimediaSystemsLesson29CompressionMethods.ppt《电子技术专业英语教程》冯新宇主编电子工业出版社《电子技术专业英语教程》2Unit29DigitalMultimediaSystems•Backgrounds•Texttour•Languageinuse–Vocabulary–Structure–Reading/writingtechniques2020/1/10《电子技术专业英语教程》3•Terminology–pixeln.【计】像素–waveletn.小波–subsampling二次抽样–singleframe单帧；一幅画面–laserdisc激光影碟，雷射影碟–chrominancen.色品，彩色信号，色度；【计】色度–Luminancen.亮度；【计】亮度–interpolationn.插入[值]，内插；插值法，内插法–rastern.光栅；【电】试映图；–patternrecognition模式识别–discretecosinetransform（DCT）离散余弦变换Backgrounds2020/1/10《电子技术专业英语教程》4•Terminology–vectorquantization矢量量化–CDTV（conventionaldefinitiontelevision）普通清晰度电视–bilevelimage二值图像，黑白图像–facsimiletransmission传真发送–entropycoding熵编码–lossycompression有损压缩–ADPCM自适应音频脉冲编码Backgrounds2020/1/10《电子技术专业英语教程》5•Terminology–motioncompensation动态补偿，运动补偿–neuralnetwork神经网络–fastFouriertransform快速傅里叶变换–DVI交互式数字视频系统–CD-I交互式CD–hybridcoding混合编码法Backgrounds2020/1/10《电子技术专业英语教程》6Texttour•Outline-Introduction-Taxonomyofcompressionapproaches•Lossycompression•Prediction•Frequency-orientedcompression•Importance-orientedcompression•Hybridcoding2020/1/10《电子技术专业英语教程》7Introduction•Compressionisessentialifaudio,images,andvideoaretobeusedindigitalmultimediaapplications.•AmegabyteofspacewouldbefilledbyroughlysixsecondsofCD-qualityaudio,asingle640×480-pixelcolorimagestoredusing24bitsperpixel,orasingleframe-1/30second-ofCIFvideo.•Nevertheless,videodiscapplicationsoftenhavemorethan20minutesofvideo,perhaps10000slides,and30minutesofstereosoundoneachlaserdiscside.AndwiththetremendousvolumeofdatathatwillbereceivedeachdayfromplannedNASAmissionsandotherscientificventures,theneedforprovencompressiontechniquesisobvious.2020/1/10《电子技术专业英语教程》8•Compressionofdigitaldatainvolvescomputationalalgorithmsthatcanbeimplementedinsoftware.•Someinvolvedigitalversionsofsignalprocessingmethods,othersinvolvepatternrecognition,andstillothersusestatisticsorcharacteristicsofparticulardatatypesorsamples.•High-speedimplementationsinvolveVLSIchips,suchasforaudiodigitalsignalprocessing,discretecosinetransform,orvectorquantizationapproaches.2020/1/10《电子技术专业英语教程》9TaxonomyofcompressionapproachesFigure35-1Selectedcompressionapproaches2020/1/10《电子技术专业英语教程》10Lossycompression•Lossyornoisycompressionmayaddartifactsthatcanbeperceived.Carefulstudyofthehumanvisualsystemhasfocusedattentiononapproachesthatcauselittleperceivedlossinquality,butachievehighcompressionratios.2020/1/10《电子技术专业英语教程》11Prediction•PredictiveapproacheslikeADPCMinvolvepredictingsubsequentvaluesbyobservingpreviousones,andtransmittingonlytheusuallysmalldifferencesbetweenactualandpredicteddata.Anexampleinvolvesmotioncompensation.Successiveframesinavideosequenceareoftenquitesimilarorhaveblocksofpixelsshiftedfromoneframetothenext-forexample,asthecamerapansorapersonmoves.Althoughitiscomputationallyexpensivetoanalyzeimagesandyieldmotionvectors,parallelcomputersorneuralnetworkscanhelpwiththeprocessing.2020/1/10《电子技术专业英语教程》12Frequency-orientedcompression•Subbandcodingcanexploitthefactthathumanshavedifferentsensitivitiestovariousspatialandtemporalfrequencycombinations.Theideaistoseparate(forexample,usingaseriesoffilters)thedifferentfrequencycombinations,andthentocodewithgreaterfidelitythefrequenciesthathumanspayparticularattentionto.Withoutsubbandcoding,allfrequencycombinationswouldbecodedidentically,sothetechniqueachieveshighperceivedqualitywithfewertotalbits.2020/1/10《电子技术专业英语教程》13Importance-orientedcompression•Othercharacteristicsofimagesbesidesfrequencyareusedasthebasisforcompression.Theprincipleistoconsiderasmoreimportantthosepartsofanimagethathumansarebetterattunedto.Anexampleofthisapproachistofilterimages,gettingridofdetailsthatcannotbeperceived,asinthelow-passfilteringdoneforreal-timevideowithDVIsystems.Anothertechniqueistoallocatemorebitstoencodeimportantpartsofanimage,suchaswhereedgesoccur,thantoencodelargehomogeneousregions,suchasthosedepictingclouds.2020/1/10《电子技术专业英语教程》14Hybridcoding•Variouscompressionapproachescanbecombined,forexample,DCTanddifferentialpulsecodemodulation,subbandcodingandDCT,ordifferentialpulsecodemodulationandvectorquantization.Generally,subbandcodingiscoupledwithvectorquantization.Systemsandstandardsforvideocompressionoftenapplymotioncompensationfortemporalcompression,transformcodingforspatialcompression,andHuffmanorarithmeticcodingforstatisticalcompression.2020/1/10《电子技术专业英语教程》15•Vocabulary–fractaltaxonomypalettediagonal•Structure•Reading/writingtechniquesLanguageinuse2020/1/10《电子技术专业英语教程》16Vocabulary2020/1/10《电子技术专业英语教程》17fractalindictionary•RSCProblemofFractalDimensioncalculationofActualFractal实际分形体维数计算中的RSC问题•FractalGraphicsBasedonMFC基于MFC的分形图形实现方法•Dlasimulationoffractalflocsandcalculationoffractionaldimemsion.絮凝体的DLA分形模拟及其分形维数的计算方法•FRACTALINTERPOLATIONBASEDONFBM基于FBM的分形插值方法•FibonacciProcessandDLAFractalFibonacci过程和DLA分形2020/1/10《电子技术专业英语教程》18fractalindictionary•FractalDimensionEstimationofSignalBasedonFractalBrownianMotionModel基于分形布朗运动模型信号分维数估计•TheFractalBETModelofAdsorption分形BET吸附模型•FractalClassificationoffoldComplexdegree褶皱复杂程度的分形分类•Goldenself?