OpenCV | OpenCV哈里斯 (Harris)角点检测

环境

  

   

    

     

    
    

     

      pip install opencv-python==3.4.2.16
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      pip install opencv-contrib-python==3.4.2.16
     
    
  
 

理论

克里斯·哈里斯（Chris Harris）和迈克·史蒂芬斯（Mike Stephens）在1988年的论文《组合式拐角和边缘检测器》中做了一次尝试找到这些拐角的尝试，所以现在将其称为哈里斯拐角检测器。

函数：cv2.cornerHarris（），cv2.cornerSubPix（）

示例代码

  

   

    

     

    
    

     

      import cv2
     
    
   

    

     

    
    

     

      import numpy as np
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      filename = 'molecule.png'
     
    
   

    

     

    
    

     

      img = cv2.imread(filename)
     
    
   

    

     

    
    

     

      gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      gray = np.float32(gray)
     
    
   

    

     

    
    

     

      dst = cv2.cornerHarris(gray,2,3,0.04)
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      #result is dilated for marking the corners, not important
     
    
   

    

     

    
    

     

      dst = cv2.dilate(dst,None)
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      # Threshold for an optimal value, it may vary depending on the image.
     
    
   

    

     

    
    

     

      img[dst>0.01*dst.max()]=[0,0,255]
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      cv2.imshow('dst',img)
     
    
   

    

     

    
    

     

      if cv2.waitKey(0) & 0xff == 27:
     
    
   

    

     

    
    

     

       cv2.destroyAllWindows()
     
    
  
 

原图

输出图

SubPixel精度的角落

  

   

    

     

    
    

     

      import cv2
     
    
   

    

     

    
    

     

      import numpy as np
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      filename = 'molecule.png'
     
    
   

    

     

    
    

     

      img = cv2.imread(filename)
     
    
   

    

     

    
    

     

      gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      # find Harris corners
     
    
   

    

     

    
    

     

      gray = np.float32(gray)
     
    
   

    

     

    
    

     

      dst = cv2.cornerHarris(gray,2,3,0.04)
     
    
   

    

     

    
    

     

      dst = cv2.dilate(dst,None)
     
    
   

    

     

    
    

     

      ret, dst = cv2.threshold(dst,0.01*dst.max(),255,0)
     
    
   

    

     

    
    

     

      dst = np.uint8(dst)
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      # find centroids
     
    
   

    

     

    
    

     

      ret, labels, stats, centroids = cv2.connectedComponentsWithStats(dst)
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      # define the criteria to stop and refine the corners
     
    
   

    

     

    
    

     

      criteria = (cv2.TERM_CRITERIA_EPS + cv2.TERM_CRITERIA_MAX_ITER, 100, 0.001)
     
    
   

    

     

    
    

     

      corners = cv2.cornerSubPix(gray,np.float32(centroids),(5,5),(-1,-1),criteria)
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      # Now draw them
     
    
   

    

     

    
    

     

      res = np.hstack((centroids,corners))
     
    
   

    

     

    
    

     

      res = np.int0(res)
     
    
   

    

     

    
    

     

      img[res[:,1],res[:,0]]=[0,0,255]
     
    
   

    

     

    
    

     

      img[res[:,3],res[:,2]] = [0,255,0]
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      cv2.imwrite('subpixel5.png',img)
     
    
  
 

输出图

参考

https://opencv-python-tutroals.readthedocs.io/en/latest/py_tutorials/py_feature2d/py_features_harris/py_features_harris.html#harris-corners

文章来源: drugai.blog.csdn.net，作者：DrugAI，版权归原作者所有，如需转载，请联系作者。

原文链接：drugai.blog.csdn.net/article/details/103044562