opencv for python

opencv显示图像：

  # -*- coding: UTF-8 -*-
 import numpy as np
 import cv2
 from matplotlib import pyplot as plt
 
 img=cv2.imread("cat.png",5)   #载入
 cv2.imshow('image',img)     #显示
 k=cv2.waitKey(0)&0xFF     #读取键盘输入，参数为在x毫秒内读取，x=0是无限等待读取
 while(k!=27 and k!=ord('s')):
     k=cv2.waitKey(0)&0xFF
 if k==27:
     cv2.destroyAllWindows()
 elif k==ord('s'):
     cv2.imwrite('mess.png',img)
     cv2.destroyAllWindows()      #关闭窗口，参数可以为窗口名

opencv载入图像，matplotlib显示：

  # -*- coding: UTF-8 -*-
 import numpy as np
 import cv2
 from matplotlib import pyplot as plt
 
 img=cv2.imread('cat.png')
 plt.imshow(img)
 plt.show()

注：彩色图像使用OpenCV 加载时是BGR 模式。但是Matplotib 是RGB模式。所以彩色图像如果已经被OpenCV 读取，那它将不会被Matplotib 正确显示。

简单画图：

  # -*- coding: UTF-8 -*-
 import numpy as np
 import cv2
 from matplotlib import pyplot as plt
 cv2.namedWindow('hello')
 img=np.zeros((512,512,3),np.uint8) #创建一张空图片
 cv2.line(img,(60,90),(511,511),(255,0,0),6);
 cv2.rectangle(img,(100,70),(300,300),(100,100,100),5)
 cv2.circle(img,(200,200),60,(0,250,0),2)
 font=cv2.FONT_HERSHEY_SIMPLEX
 cv2.putText(img,'opencv',(60,400),font,4,(25,25,90),2)
 cv2.imshow('hello',img)
 
 cv2.waitKey(0)
 cv2.destroyAllWindows()

鼠标事件：

  # -*- coding: UTF-8 -*-
 import numpy as np
 import cv2
 from matplotlib import pyplot as plt
 #鼠标事件回调函数 函数参数统一如此
 def draw_rectangle(event,x,y,flags,param):
     if event==cv2.EVENT_LBUTTONDBLCLK:
         cv2.rectangle(img,(x,y),(x+30,y+30),(250,20,20),5)
 
 img=np.zeros((512,512,3),np.uint8)
 cv2.namedWindow('hello')
 cv2.setMouseCallback('hello',draw_rectangle)
 while 1:
     cv2.imshow('hello',img)
     if cv2.waitKey(20)&0xFF==27:
         break;
 cv2.destroyAllWindows()

滑动条：

 # -*- coding: utf-8 -*-
 """
 Created on Sun Jan 5 13:51:34 2014
 @author: duan
 """
 import cv2
 import numpy as np
 def nothing(x):            #滑动条的位置，通常默认为pass
     pass
 # 创建一副黑色图像
 img=np.zeros((250,512,3),np.uint8)
 cv2.namedWindow('image')
 cv2.createTrackbar('R','image',0,255,nothing)    #创建滑动条    ，滑动条名称，显示窗口名称，范围，回调函数
 cv2.createTrackbar('G','image',0,255,nothing)
 cv2.createTrackbar('B','image',0,255,nothing)
 switch='0:OFF\n1:ON'
 cv2.createTrackbar(switch,'image',0,1,nothing)
 while(1):
     cv2.imshow('image',img)
     k=cv2.waitKey(20)&0xFF
     if k==27:
         break
     r=cv2.getTrackbarPos('R','image')
     g=cv2.getTrackbarPos('G','image')
     b=cv2.getTrackbarPos('B','image')
     s=cv2.getTrackbarPos(switch,'image')
     if s==0:
         img[:]=100
     else:
         img[:]=[b,g,r]
 cv2.destroyAllWindows()

利用滑动条改变颜色画圆：

 # -*- coding: utf-8 -*-
 import cv2
 import numpy as np
 r,b,g=0,0,0
 def nothing(x):            #滑动条的位置，通常默认为pass
     pass
 
 def draw_circle(event,x,y,flags,param):
     if event==cv2.EVENT_LBUTTONDBLCLK:
         cv2.circle(img1,(x,y),10,(b,g,r),-1)
 
 # 创建一副黑色图像
 img=np.zeros((250,512,3),np.uint8)
 img1=np.zeros((250,512,3),np.uint8)
 
 cv2.namedWindow('image')
 cv2.namedWindow('win')
 
 cv2.createTrackbar('R','image',0,255,nothing)    #创建滑动条    ，滑动条名称，显示窗口名称，范围，回调函数
 cv2.createTrackbar('G','image',0,255,nothing)
 cv2.createTrackbar('B','image',0,255,nothing)
 
 cv2.setMouseCallback('win',draw_circle)
 while(1):
     cv2.imshow('win',img1)
     cv2.imshow('image',img)
     if cv2.waitKey(20)&0xFF==27:
         break
     r=cv2.getTrackbarPos('R','image')
     g=cv2.getTrackbarPos('G','image')
     b=cv2.getTrackbarPos('B','image')
     img[:]=[b,g,r]
 cv2.destroyAllWindows()