Python | OpenCV BGR color palette with trackbars

Last Updated : 04 Jan, 2023

OpenCV is a library of programming functions mainly aimed at real-time computer vision. In this article, Let's create a window which will contain RGB color palette with track bars. By moving the trackbars the value of RGB Colors will change b/w 0 to 255. So using the same, we can find the color with its RGB values.

Libraries needed: OpenCV Numpy

Approach: Create a black window with three color channels with resolution 512 x 512. Then create three 'B' 'G' 'R' trackbars using predefined functions of OpenCV library. Set the values of channels from 0 to 255. Merging the black window with these color trackbars.

Python3 1==

# Python program to create RGB color  # palette with trackbars  # importing libraries import cv2 import numpy as np   # empty function called when # any trackbar moves def emptyFunction():  pass   def main():    # blackwindow having 3 color chanels  image = np.zeros((512, 512, 3), np.uint8)   windowName ="Open CV Color Palette"    # window name  cv2.namedWindow(windowName)     # there trackbars which have the name  # of trackbars min and max value   cv2.createTrackbar('Blue', windowName, 0, 255, emptyFunction)  cv2.createTrackbar('Green', windowName, 0, 255, emptyFunction)  cv2.createTrackbar('Red', windowName, 0, 255, emptyFunction)    # Used to open the window  # till press the ESC key  while(True):  cv2.imshow(windowName, image)    if cv2.waitKey(1) == 27:  break    # values of blue, green, red  blue = cv2.getTrackbarPos('Blue', windowName)  green = cv2.getTrackbarPos('Green', windowName)  red = cv2.getTrackbarPos('Red', windowName)    # merge all three color chanels and  # make the image composites image from rgb   image[:] = [blue, green, red]  print(blue, green, red)    cv2.destroyAllWindows() # Calling main()  if __name__=="__main__":  main()