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ID:62111046
大小:1.61 MB
页数:44页
时间:2021-04-17
《最新基于肤色模型和模板匹配的人脸检测.教学讲义ppt.ppt》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、基于肤色模型和模板匹配的人脸检测.IntroductionThemethodconsistsintwoimageprocessingsteps.First.separateskinregionsfromnon-skinregions.Afterthat,locatethefrontalhumanface(s)withintheskinregions.Inthefirststep,achromachartthatshowslikelihoodsofskincolorsisobtained.Thischromachartisusedtogenerateagraysc
2、aleimagefromtheoriginalcolorimage.Thisimagehasthepropertythatthegrayvalueatapixelshowsthelikelihoodofthatpixelofrepresentingtheskin.Thensegmentsthegrayscaleimagetoseparateskinregionsfromnonskinregions.9/1/20212Inthesecondstep,theluminancecomponentitselfisusedthen,togetherwithtemplate
3、matchingtodetermineifagivenskinregionrepresentsafrontalhumanfaceornot.OriginalImageSkin-likelihoodImageSkin-segmentedImageImageandTemplateFaceFinalDetectionImageprocessingsequenceforfacedetection9/1/20213WiththisGaussianfittedskincolormodel,wecannowobtainthelikelihoodofskinforanypixe
4、lofanimage.Therefore, ifapixel,havingtransformfromRGBcolorspacetochromaticcolorspace,hasachromaticpairvalueof(r,b),thelikelihoodofskinforthispixelcanthenbecomputedasfollows:9/1/20217Hence,thisskincolormodelcantransformacolorimageintoagrayscaleimagesuchthatthegrayvalueateachpixelshows
5、thelikelihoodofthepixelbelongingtotheskin.Withappropriatethresholding,thegrayscaleimagescanthenbefurthertransformedtoabinaryimageshowingskinregionsandnon-skinregions.TheOriginalcolorImageTheskin-likelihoodimage.9/1/20218SkinSegmentationTheskin-likelihoodimagerevealedthatallskinregion
6、s(liketheface,thehandsandthearms)wereshownbrighterthanthenon-skinregion,theskinregionscanbesegmentedfromtherestoftheimagethroughathresholdingprocess.Sincepeoplewithdifferentskinshavedifferentlikelihood,anadaptivethresholdingprocessisrequiredtoachievetheoptimalthresholdvalueforeachrun
7、.9/1/20219Theadaptivethresholding:Theadaptivethresholdingisbasedontheobservationthatsteppingthethresholdvaluedownmayintuitivelyincreasethesegmentedregion.However,theincreaseinsegmentedregionwillgraduallydecrease(aspercentageofskinregionsdetectedapproaches100%),butwillincreasesharplyw
8、henthethresh
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