Python-OpenCV 杂项（一）：图像绘制

0x00. 绘制直线

import numpy as np
import cv2
img = np.zeros((512,512,3), np.uint8)

cv2.line(img,(0,0),(511,511),(255,0,0),5)
cv2.imshow('image',img)
cv2.waitKey(0)
cv2.destroyAllWindows()

0x01. 绘制矩形

cv2.rectangle(img,(384,0),(510,128),(0,255,0),3)

0x02. 画圆

cv2.circle(img,(447,63), 63, (0,0,255), -1)

0x03. 画椭圆

cv2.ellipse(img,(256,256),(100,50),0,0,180,255,-1)

0x04. 绘制多边形

pts = np.array([[10,5],[20,30],[70,20],[50,10]], np.int32)
pts = pts.reshape((-1,1,2))
img = cv2.polylines(img,[pts],True,(0,255,255))

0x05. 添加文本

font = cv2.FONT_HERSHEY_SIMPLEX
cv2.putText(img,'OpenCV',(10,500), font, 4,(255,255,255),2,cv2.LINE_AA)

0x06. 一个调色板

import cv2
import numpy as np

def nothing(x):
    pass

# Create a black image, a window
img = np.zeros((300,512,3), np.uint8)
cv2.namedWindow('image')

# create trackbars for color change
cv2.createTrackbar('R','image',0,255,nothing)
cv2.createTrackbar('G','image',0,255,nothing)
cv2.createTrackbar('B','image',0,255,nothing)

# create switch for ON/OFF functionality
switch = '0 : OFF \n1 : ON'
cv2.createTrackbar(switch, 'image',0,1,nothing)

while(1):
    cv2.imshow('image',img)
    k = cv2.waitKey(1) & 0xFF
    if k == 27:
        break

    # get current positions of four trackbars
    r = cv2.getTrackbarPos('R','image')
    g = cv2.getTrackbarPos('G','image')
    b = cv2.getTrackbarPos('B','image')
    s = cv2.getTrackbarPos(switch,'image')

    if s == 0:
        img[:] = 0
    else:
        img[:] = [b,g,r]

cv2.destroyAllWindows()

from: https://segmentfault.com/a/1190000003804926?_ea=373620