opencv_trackbars_example.py

opencv_trackbars_example.py

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()