CODEWITHSUNDEEP
pythonmacospython-3.xopencvubuntu
Chandramauli Kaushik
Chandramauli Kaushik

Reputation: 39

OpenCV - Python trackbars not working on macOS, but works fine in Ubuntu

I am running a code which I got from a website, the code runs completely fine on Ubuntu but the trackbars don't move on macOS :

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()

This is the image from my macbook where the trackbars don't move:

This is the image from my macbook where the trackbars don't move

Why does this happen? Please help. Thanks.

Upvotes: 2

Views: 2414

Answers (2)

Yassine Açoine
Yassine Açoine

Reputation: 41

This issue has been fixed if you update your cv2 with:

pip install opencv-python-rolling

Upvotes: 4

Maen
Maen

Reputation: 815

if/else statement should be inside while loop


import cv2
import numpy as np

def nothing(x):
   pass

img = np.zeros((300,512,3), np.uint8)
cv2.namedWindow('image')

cv2.createTrackbar('R','image',0,255,nothing)
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(1) & 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[:] = 0
    else:
        img[:] = [b,g,r]

cv2.destroyAllWindows()

Upvotes: 0

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