JPEG-Still Image Compression Standard.ppt

JPEG--PilaniSource:Chapter3ofJPEG—pression:Concepts,AlgorithmsandVLSIArchitecturesby TinkuAcharya and Ping-SingTsai13-Feb-putingTopicstoday…pressionProgressiveDCT-BasedModeHierarchicalMode13-Feb-pressionstandardforcontinuoustonestillimagesAcronymforJointPhotographicExpertsGroupOfficiallyreferredtoasISO/IECIS(InternationalStandard)10918-1:pressionandCodingofContinuous-toneStillImagesITU--Feb-putingIntroduction[2]pressionofcontinuous-pressionperformanceatornearthestate-of-the-artwithuser-pressionratiosandwithverygoodtoexcellentreconstructedquality13-Feb-putingIntroduction[3]-presstheimageinasinglescanusingDCT-,thedecodedimageisnotanexactreplica,-essivescanproducingabetter--Feb-putingIntroduction[4]Modes2,3and4arelossyMode1usespredictivecodingwithnoquantization,hencelosslessSequentialDCT-basedJPEGalgorithmInit’ssimplestformcalledbaselineJPEGalgorithm,odingforentropyencoding13-Feb-putingTheJPEGLosslessCodingAlgorithmBasedontheprincipleofpredictivecoding,asimplemethodforspatialredundancyreductionThedifferencebetweentheactualpixelvalueandthepredictedvalueiscalledthedifferentialorthepredictionerrorvalue&isentropyencodedusingavariable-lengthencodingtechniqueDifferentialPulseCodeModulation(DPCM)??13-Feb-putingTheJPEGLosslessCodingAlgorithm[2]ThevalueofthepixelinlocationXispredictedusingoneormoreofthe3-neighborsasshowninfig-(a)Thenthepredictionerror/predictionresidualiscodedusingHuffmancoding/odingFig(a):3-pixelneighborhoodforpixelXFig(b):EncoderDiagramforLosslessmode13-Feb-putingTheJPEGLosslessCodingAlgorithm[3]EightpossibleoptionsforpredictionsOption-pressioninhierarchicalmodeOptions1-3are1-DimensionalPredictorsOptions4-7are2-pressedfileOptionPredictionFunctionTypeOfPrediction0N