初识OpenCV-Python - 004: Trackbar as the color palette

Posted 2021-03-25 august2019

此次学习了如何用OpenCV建立一个色调盘。其中会用到cv2.getTrackbarPos(), cv2.createTrackbar()函数。

code:

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) #建立一个调节红色的横条
cv2.createTrackbar(‘G‘,‘image‘,0,255,nothing)
cv2.createTrackbar(‘B‘,‘image‘,0,255,nothing)

#create switch for ON/OFF functionality
switch = ‘0 : OFF 
1 : 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‘) #记录当前红色条的数据
    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()

Code结果展示: