opencv for python

opencv显示图像：

 1  # -*- coding: UTF-8 -*-
 2 import numpy as np
 3 import cv2
 4 from matplotlib import pyplot as plt
 5
 6 img=cv2.imread("cat.png",5)   #载入
 7 cv2.imshow(‘image‘,img)     #显示
 8 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
 9 while(k!=27 and k!=ord(‘s‘)):
10     k=cv2.waitKey(0)&0xFF
11 if k==27:
12     cv2.destroyAllWindows()
13 elif k==ord(‘s‘):
14     cv2.imwrite(‘mess.png‘,img)
15     cv2.destroyAllWindows()      #关闭窗口，参数可以为窗口名

opencv载入图像，matplotlib显示：

1  # -*- coding: UTF-8 -*-
2 import numpy as np
3 import cv2
4 from matplotlib import pyplot as plt
5
6 img=cv2.imread(‘cat.png‘)
7 plt.imshow(img)
8 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：

 1  # -*- coding: UTF-8 -*-
 2 import numpy as np
 3 import cv2
 4 from matplotlib import pyplot as plt
 5 cv2.namedWindow(‘hello‘)
 6 img=np.zeros((512,512,3),np.uint8) #创建一张空图片
 7 cv2.line(img,(60,90),(511,511),(255,0,0),6);
 8 cv2.rectangle(img,(100,70),(300,300),(100,100,100),5)
 9 cv2.circle(img,(200,200),60,(0,250,0),2)
10 font=cv2.FONT_HERSHEY_SIMPLEX
11 cv2.putText(img,‘opencv‘,(60,400),font,4,(25,25,90),2)
12 cv2.imshow(‘hello‘,img)
13
14 cv2.waitKey(0)
15 cv2.destroyAllWindows()

鼠标事件：

 1  # -*- coding: UTF-8 -*-
 2 import numpy as np
 3 import cv2
 4 from matplotlib import pyplot as plt
 5 #鼠标事件回调函数 函数参数统一如此
 6 def draw_rectangle(event,x,y,flags,param):
 7     if event==cv2.EVENT_LBUTTONDBLCLK:
 8         cv2.rectangle(img,(x,y),(x+30,y+30),(250,20,20),5)
 9
10 img=np.zeros((512,512,3),np.uint8)
11 cv2.namedWindow(‘hello‘)
12 cv2.setMouseCallback(‘hello‘,draw_rectangle)
13 while 1:
14     cv2.imshow(‘hello‘,img)
15     if cv2.waitKey(20)&0xFF==27:
16         break;
17 cv2.destroyAllWindows()

滑动条：

 1 # -*- coding: utf-8 -*-
 2 """
 3 Created on Sun Jan 5 13:51:34 2014
 4 @author: duan
 5 """
 6 import cv2
 7 import numpy as np
 8 def nothing(x):            #滑动条的位置，通常默认为pass
 9     pass
10 # 创建一副黑色图像
11 img=np.zeros((250,512,3),np.uint8)
12 cv2.namedWindow(‘image‘)
13 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
14 cv2.createTrackbar(‘G‘,‘image‘,0,255,nothing)
15 cv2.createTrackbar(‘B‘,‘image‘,0,255,nothing)
16 switch=‘0:OFF\n1:ON‘
17 cv2.createTrackbar(switch,‘image‘,0,1,nothing)
18 while(1):
19     cv2.imshow(‘image‘,img)
20     k=cv2.waitKey(20)&0xFF
21     if k==27:
22         break
23     r=cv2.getTrackbarPos(‘R‘,‘image‘)
24     g=cv2.getTrackbarPos(‘G‘,‘image‘)
25     b=cv2.getTrackbarPos(‘B‘,‘image‘)
26     s=cv2.getTrackbarPos(switch,‘image‘)
27     if s==0:
28         img[:]=100
29     else:
30         img[:]=[b,g,r]
31 cv2.destroyAllWindows()

利用滑动条改变颜色画圆：

 1 # -*- coding: utf-8 -*-
 2 import cv2
 3 import numpy as np
 4 r,b,g=0,0,0
 5 def nothing(x):            #滑动条的位置，通常默认为pass
 6     pass
 7
 8 def draw_circle(event,x,y,flags,param):
 9     if event==cv2.EVENT_LBUTTONDBLCLK:
10         cv2.circle(img1,(x,y),10,(b,g,r),-1)
11
12 # 创建一副黑色图像
13 img=np.zeros((250,512,3),np.uint8)
14 img1=np.zeros((250,512,3),np.uint8)
15
16 cv2.namedWindow(‘image‘)
17 cv2.namedWindow(‘win‘)
18
19 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
20 cv2.createTrackbar(‘G‘,‘image‘,0,255,nothing)
21 cv2.createTrackbar(‘B‘,‘image‘,0,255,nothing)
22
23 cv2.setMouseCallback(‘win‘,draw_circle)
24 while(1):
25     cv2.imshow(‘win‘,img1)
26     cv2.imshow(‘image‘,img)
27     if cv2.waitKey(20)&0xFF==27:
28         break
29     r=cv2.getTrackbarPos(‘R‘,‘image‘)
30     g=cv2.getTrackbarPos(‘G‘,‘image‘)
31     b=cv2.getTrackbarPos(‘B‘,‘image‘)
32     img[:]=[b,g,r]
33 cv2.destroyAllWindows()