Python OpenCV处理图像之图像直方图和反向投影
本文实例为大家分享了PythonOpenCV图像直方图和反向投影的具体代码，供大家参考，具体内容如下
当我们想比较两张图片相似度的时候，可以使用这一节提到的技术
直方图对比
反向投影
关于这两种技术的原理可以参考我上面贴的链接，下面是示例的代码：
0x01.绘制直方图
importcv2.cvascv
defdrawGraph(ar,im,size):#Drawthehistogramontheimage
minV,maxV,minloc,maxloc=cv.MinMaxLoc(ar)#Gettheminandmaxvalue
hpt=0.9*histsize
foriinrange(size):
intensity=ar[i]*hpt/maxV#Calculatetheintensitytomakeenterintheimage
cv.Line(im,(i,size),(i,int(size-intensity)),cv.Scalar(255,255,255))#Drawtheline
i+=1
#----Grayimage
orig=cv.LoadImage("img/lena.jpg",cv.CV_8U)
histsize=256#Becauseweareworkingongrayscalepictureswhichvalueswithin0-255
hist=cv.CreateHist([histsize],cv.CV_HIST_ARRAY,[[0,histsize]],1)
cv.CalcHist([orig],hist)#Calculatehistogramforthegivengrayscalepicture
histImg=cv.CreateMat(histsize,histsize,cv.CV_8U)#Imagethatwillcontainthegraphoftherepartitionofvalues
drawGraph(hist.bins,histImg,histsize)
cv.ShowImage("OriginalImage",orig)
cv.ShowImage("OriginalHistogram",histImg)
#---------------------
#----Equalizedimage
imEq=cv.CloneImage(orig)
cv.EqualizeHist(imEq,imEq)#Equlizetheoriginalimage
histEq=cv.CreateHist([histsize],cv.CV_HIST_ARRAY,[[0,histsize]],1)
cv.CalcHist([imEq],histEq)#Calculatehistogramforthegivengrayscalepicture
eqImg=cv.CreateMat(histsize,histsize,cv.CV_8U)#Imagethatwillcontainthegraphoftherepartitionofvalues
drawGraph(histEq.bins,eqImg,histsize)
cv.ShowImage("ImageEqualized",imEq)
cv.ShowImage("EqualizedHIstogram",eqImg)
#--------------------------------
cv.WaitKey(0)
0x02.反向投影
importcv2.cvascv
im=cv.LoadImage("img/lena.jpg",cv.CV_8U)
cv.SetImageROI(im,(1,1,30,30))
histsize=256#Becauseweareworkingongrayscalepictures
hist=cv.CreateHist([histsize],cv.CV_HIST_ARRAY,[[0,histsize]],1)
cv.CalcHist([im],hist)
cv.NormalizeHist(hist,1)#Thefactorrescalevaluesbymultiplyingvaluesbythefactor
_,max_value,_,_=cv.GetMinMaxHistValue(hist)
ifmax_value==0:
max_value=1.0
cv.NormalizeHist(hist,256/max_value)
cv.ResetImageROI(im)
res=cv.CreateMat(im.height,im.width,cv.CV_8U)
cv.CalcBackProject([im],res,hist)
cv.Rectangle(im,(1,1),(30,30),(0,0,255),2,cv.CV_FILLED)
cv.ShowImage("OriginalImage",im)
cv.ShowImage("BackProjected",res)
cv.WaitKey(0)
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持毛票票。