第六章彩色图像处理

第六章 InstituteofArtificial ligenceandContentColorFundamentals（颜色基础ColorModels（颜色模型ImageSegmentationBasedonColor（基于彩色的图像分割InstituteofArtificial ContentColorFundamentals（颜色基础ColorModels（颜色模型ImageSegmentationBasedonColor（基于彩色的图像分割InstituteofArtificial ColorFundamentalsWhydoesavisualsystemneed lwhatfoodisTodistinguishmaterialchangesfromshadingTogrouppartsofoneobjecttogetherinaTofindpeople’sCheckwhethera ’sappearancelooksInstituteofArtificial ColorHowtocaptureColorFundamentalsLightspectrumanduInstit白炽灯 uColorFundamentalsIsaacNewton,InstituteofArtificial ColorFundamentalsInstituteofArtificial ColorFundamentalsThecolorsthathumansperceiveinanobjectaredeterminedbythenatureofthelightreflectedfromtheobject.e.g.greenobjectsreflectlightwithwavelengthsprimarilyinthe500to570nmrangewhileabsorbingmostoftheenergyatotherwavelength

InstituteofArtificial ColorFundamentals66 InstituteofArtificial ColorFundamentals –700nmGreen–546.1nm –InstituteofArtificial R+G+B=R+G=R+B=G+B=CC-B=(G+B)-B=W-B=(R+G+B)-B=R+G=Y黄色、M品红色、CR+G=YR+B=MG+B=CColorFundamentalsThecharacteristicsgenerallyusedtodistinguishonecolorfromanotherarebrightness,hue,andsaturationBrightness亮度)theachromaticnotionofHue色调):dominantwavelengthinamixtureoflightwaves,representsdominantcolorasperceivedbyanSaturation饱和度)relativepurityortheamountoflightmixedwithitsInstituteofArtificial ColorFundamentalsTristimulus（三激色）valuesformedbyRed,green,andbluearedenotedX,YandZ,respectively.Acolorisdefinedbyitstrichromaticcoefficients,definedx XYy XYz XY

𝑥+𝑦+𝑧=InstituteofArtificial CIECIEChromaticityItshowscolorcompositionasafunctionofx(red)andy(green)ContentColorFundamentals（颜色基础ColorModels（颜色模型ImageSegmentationBasedonColor（基于彩色的图像分割InstituteofArtificial ColorModelsColorscanbearrangedindifferentwaysbasedonAmountofred,greenorThesecanbethoughtofasdifferentdimensionsorparametersofcolorThreedimensionssufficestoarrangeallButdifferentdimensionscanbeTheresultofchoosingasetofdimensionsisacolorspace颜色空间InstituteofArtificial ColorModelsThereareseveralwaystoencodecolorinformation,eachonedefiningadifferentcolorspace.SomecommonlyusedcolorspacesRGB(red,green,blue)isusedtodescribecoloronelectronicscreens.CMY(cyan,magenta,yellow)andCMYK(cyan,magenta,yellow,black)areusedtodescribecolorprintedonpaper.HSI(hue,saturation,intensity)isanintuitivecolorusedbyInstituteofArtificial ColorModelsRGBcolorrelatedtohumanvisionthroughthetristimulustheoryofcolorvision.TheRGBisanadditivecolormodel.Theprimaryred,greenandbluearecombinedtoreproduceotherIntheRGBcolorspace,acolorisrepresentedbya[0,1]orInstituteofArtificial ColorModelsRGBcolorØTheadditivecolorØThisisthecolorspacewe’retothinkingaboutinAmountof“red”Amountof“green”Amountof“blue”ØTheproblemisthat“red”variesfromoutputdevicetooutputColorInstituteofArtificial ColorModelsRGBcolorPixelThetotalnumberofcolorsina24-bitRGBimageis(28)3=InstituteofArtificial Constructionofcolorimagefromcolor++ColorModelsTheCMYcolorØThesubtractiveforØEachprimaryisthecomplementofanadditiveCyan(anti-Magenta(anti-ØCMYKisusedintheprintingindustryK(blackink)addedforbetterreproductionofgrayInstituteofArtificial ColorModelsTheCMYcolor InstituteofArtificial ColorModelsTheCMYcolorTheCMYcolourspaceisalsorepresentedbyaunitcube.Thewhiteisthe(0,0,0)andtheblackisthe(1,1,1).MYCInstituteofArtificial cc m1g10 r TheCMYcolorTheconversionfromRGBtoCMYisgivenbythec r 1 1 Example:TheredcoloriswritteninRGBas(1,0,0).InCMYitiswrittenasandyellowInstituteofArtificial ColorModelsTheCMYandCMYKColorEqualamountsofthepigmentprimaries,cyan,magenta,andyellowshouldproduceblack.Inpractice,combiningthesecolorsforprintingproducesmuddy-lookingToproducetrueblack,thepredominantcolorinprinting, color,black,isadded,givingrisetotheCMYKcolormodel.ColorModelsCMYKcartridgesforcolorInstituteofArtificial ligenceandCMYvs.ColorModelsHSIColorHue（色调）dominantwavelengthinamixtureoflightwaves,representsdominantcolorasperceivedbyanobserver.Saturation（饱和度）relativepurityortheamountofwhitelightmixedwithitshue.Intensity(强度)theachromaticnotionofInstituteofArtificial ligenceandHSIColorHSIColorHSIColorModelsHSIColor–ConvertingColorsfromRGBto ifB

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