包装工程概论第9课

COLORofPACKAGEIntroductionColoristhefirstthinganobservernoticesaboutapackage.Itisrecognizedbeforeshape,andthegraphicortextcontentisrecognizedlast.Assuch,colorisoneofthemostimportantmotivatorsofapurchasedecision.Colorevokesanemotionalresponsefromtheobserver.Colorisassociatedwithmoods,feelings,places,andthings.Thatwerelatecolortoemotionsisevidencedbytheuseofcolorstodescribeparticularemotionalstates.Wesayweare"feelingblue","sawred",are"greenwithenvy",havea"purplerage",orareina"blackmood".Red,orange,yellow,andbrownshadesare"warm"colors,whilegreensandbluesare"cool"colors.Colorhasweight,size,andmovement.Generally,brightercolorswillappearlargethandarkcolorsinbarsofthesamesize.Ayellowcircletendstomoveorradiateoutward,whileabluecircleconveysinwardmovement.Colorcaninfluenceperceptionssuchassize,quality,value,andflavor,tonameofafew.Todemonstratedifferenceinproductperceptionbasedoncoloralone,matchedgroupsofpeopleansweredanumberofquestionsaboutcrackers.Thecrackerswereactuallyidentical,theonlydifferencesbeingthepackagecolor.Packagecolorwasshowntohaveasignificantinfluenceonperceptionofflavor.Colorhasethnicandsocialassociations.Forexample,insameAsiancountrieswhiteisthecolorofmourning.Greenandorangecombinations,rarelyusedinNorthAmerica,arecommoninIndia,astheyarethenationcolors.Red,white,andgreencombinationsareusedonpackagestryingtocreateanItalianflavor.Althoughthereissometendencyforcolorstocomeinandoutinfashion,certaincolorstendtodominatethemarketplace.Asupermarketcheckwillshowapredominanceofreds,browns,andbluesandanalmosttotalabsenceofpurple.Therearefewuniversalruleswhendecidingonwhatcolorstomakeapackage.Foreverystatedruleforselectingcolors,apackagecanbefoundthatsuccessfullydefiestherule.Sufficeittosaythatcolorsmustbeselectedtorepresentthepersonaofthepackagedesignandtheperceptionsofthetargetedaudience.ColorPerceptionTheeyeisacomplexorganthatreceiveslightandsendsstimulitothebrainforinterpretation.Colorperception,dependsontheeye'sreceptorsandthepsychologyofhowthebraininterpretsthemessage.We"see"withourbrains,notwithoureyes.Thenormalhumaneyehasastructurewithindividualreceptorssensitivetored,green,andbluepartsofthespectrum(peoplewhoarecolor-blindhavereducedsensitivityinoneorseveralcolorreceptors).Aswellasdetectingdifferencesinwavelength,thehumaneyeisthoughttohaveaseparatefunctionthatdeterminesbrightness.Anycolorinthespectrumcanbematchedbycombiningthesestimuliintheproperproportions.Thehumaneyecandifferentiateseveralmillioncolors.Youcanappreciatetheproblemofverbalcommunicationwhenyouconsiderthatthereareonlyaboutadozenspecificcolornames.Thehumaneyedoesnotdetectallcolorsequally.Sensitivityfallsofateitherendofthevisiblespectrum.Yellowsarethebrightestcolorstothehumaneye.Thegreatestperceivedcontrastisbetweenblackandyellow,notblackandwhite,asmightbesupposed.Perceivedcolordependsontheproportionofstimulationgiveneachcolorreceptor.Whenallreceptorsareequallystimulated,weexperiencethesensationof“white".Ifnoreceptorsarestimulated,weexperienceblack,theabsenceofcolor(Forconvenience,blackiscalledacolor).ColorTerminologyHue:Thecolor'spositioninthespectrum.Thequalitydifferentiatesbetweennamedcolorssuchasred,yellow,green,blue,andpurple.black-and-whitephotograph.Chroma:Howstronglycoloredtheobjectisorhowmuchthecolordiffersinitsstrengthofcolorfromagraysampleofthesamevalue.Inpackaging,chromaisusuallyreferredtoassaturation.Saturationandvaluereflectthecolordifferenceswhenabasecolorismixedprogressivelymorewhiteforalighter,lesssaturatedcolor(atint)ormixedwithprogressivelymoreblackforadarkvalue(atone).Brightness,whenusedtodescribecolors,describesthetotalamountofrefectedwavelengthparticulartoacolor.Whenusedtodescribepaper,brightnessreferstothetotalamountofwhitelightreflectedbackcomparedwithpuremagnesiumoxide,whichhasbeenarbitrarilyassignedavalueof100units.Brightnessisakeyattributewhenconsideringasubstrateforprinting.Mostpackageprintinginksaretransparent;lightpassesthroughthemandisreflectedfromthesubstratesurfacebacktotheobserver.Ifthesubstratesurfaceisbright,thenallwavelengthsnotabsorbedbythepigmentarereflectedback.However,ifthesubstrateabsorbssomepercentageofred,green,andblue,thentheperceivedreflectedcolorwillnotappearasbright.ViewingColorColorperceptionishighlysubjectiveanddependson:Thelightilluminatingtheobject.Thenatureoftheobjectitself.Lightfromdifferentsourceshasdifferentwavelengthcomposition.Forexample,incandescentlightsarerichintheredendofthespectrum,whilemostfluorescentlightsaredeficientinreds.Sincecolorisanattributeofincidentlight,colorappeardifferentunderthesetwolightsources.Industriesworkingwithcolorhavestandardizedviewingilluminationstoreducecolor-matchingproblems.Theseareusuallystatedasthecolortemperatureof5000Kelvin(K).Atlowtemperatures,aheatedobjectradiatesenergyintheinfraredrange,detectedasradiatedheat.Asthetemperaturerises,thereismoreradiationintheshorterwavelengths,andtheeyedetectsadullred.Athightemperatures,theobjectradiatesacrossabroadspectralbandcoveringallvisiblewavelengths,andtheeyesees"whiteheat".Graphicartslightcompositionforthepurposeofcolorcomparisonisinternationallystandardizedat5000K,andvisualcolorcomparisonsshouldbedoneundertheseconditions.Acolortemperatureof5000Kissimilartooutdoorlightingataboutnoon.2.ObjectTheobjectitselfinfluencescolorperception.surfacetexture,gloss,geometry,andsurroundingoradjacentcolorsallaffectjudgmentofthesubjectcolor.Someobjecteffectspromoteopticalillusions.3.ObserverThegreatestvariableofallisthepersonviewingthecolor.Eveneliminatingthosewhohavepoorsensitivityincertainwavelengths(colorblindness)stillleavesquestionsofpersonalemotionsandpreferences.Thebrainmakesadjustmentsbasedonexperiencetothesignalsreceivedfromtheeyes.Anobjectviewedunderafluorescentlightthathaslittleredcomponentcolor-correctedbythebraintomakeitlooknormalaccordingtoourexperience.Photographstakenunderthesamelighttellthetruth:thescenewillhaveanoverallgreencast.Thebrainalterscolorperceptionsinwaysthatcannotbecontrolled,andtheeyeastheprimaryreceptorsuffersfromanumberofirregularities,suchasafterimageandfatigue.Forthisreason,themostobjectivecolormeasurementsaredoneinstrumentallywithcolorimetersordensitometers.Theseinstrumentsassignnumericalvaluestotheamountofeachcolorcomponentreflected.Theproblemwith"objective"instrumentalcolormeasurement,however,isthattheinstrumentmakesnoallowanceforshapes,adjacentcolors,textures,andotherfactorsthataffecthumancolorperception.Suchcolorimetrywillnottelluswhetheragraphicimage"looksright";itcanonlyverifythattheinksandpapersarethesameasthoseusedonthelastjoborarethesameasinaselectedcontrolsample.Moreoftenacolorisfirstidentifiedbyapanelofhumanobservers,andthenacolorimetricinstrumentisbroughtintoquantifythecolorforspecificationorcontrolpurposes.AdditionalContentTestMethodforProductFragilityJustastheweightoftheproductcanbemeasuredusingascale,theproductruggednesscanbemeasuredwithdynamicinputs.Ashockmachineisusedtogeneratedadamageboundarycurve,andavibrationsystemisusedtomapoutthenaturalfrequenciesofaproduct.Shock:DamageBoundaryShockdamagetoproductsresultsfromexcessiveinternalstressinducedbyinertiaforces.Sinceinertiaforcesaredirectlyproportionaltoacceleration(F=ma),shockfragilityischaracterizedbythemaximumtolerableaccelerationlevel,i.e,howmanyg'stheitemcanwithstand.Whenadroppedpackagestrikesthefloor,localaccelerationatthecontainersurfacecanreachseveralhundredg's.Thepackagematerialchangestheshockpulsedeliveredtotheproductsothatthemaximumaccelerationisgreatlyreduced(andthepulsedurationismanytimeslonger).Itisthepackagedesigner'sgoaltobesurethattheg-leveltransmittedtotheitembythecushionislessthattheg-levelwhichwillcausetheitemtofail.Thedamageboundarytheoryisatestingprotocolwhichdeterminesinanengineeringsense,whichshockinputswillcausedamagetoaproductandwhichwillnot.Therearetwopartsofashockwhichcancausedama