Python | OpenCV BGR color palette with trackbars

Michael Zippo 18.07.2021

OpenCV — is a library of programming functions mainly for real-time computer vision.
In this article, let’s create a window that will contain an RGB color palette with track stripes. By moving the trackbars, the RGB Colors value will change from 0 to 255. So using the same we can find a color with its RGB values.

  Libraries needed:  OpenCV Numpy

Fit:
Create a black window with three color channels at 512 x 512 resolution. Then create three trackbars & # 39; B & # 39; & # 39; G & # 39; & # 39; R & # 39; using the predefined functions of the OpenCV library. Set channel values from 0 to 255. Merges a black box with these colored trackbars.

# Python program for creating RGB color
# palette with trackbars

# import libraries

import cv2

import numpy as np

# empty function is called when
# any trackbar movement

def emptyFunction ():

pass

def main ():

# black window with 3 color channels

image = np.zeros (( 512 , 512 , 3 ), np.uint8)

windowName = "Open CV Color Palette"

# window name

cv2.namedWindow (windowName)

# there are trackbars named

Number of trackbars min. and max. values

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

   # before clicking ESC keys  
   while   (  True  ): 
   cv2.imshow (windowName, image) 
   
   if   cv2.waitKey (  1  )   =   =   27  : 
   break  
   
   # blue values , green , red  
   blue   =   cv2.getTrackbarPos (  ’Blue’  , windowName)  
   green   =   cv2.getTrackbarPos ( ’ Green’  , windowName) 
   red   =   cv2.getTrackbarPos (  ’Red’  , windowName) 
    
   # combine all three color channels and  
   # make the image a composite image from rgb  
 < p>  image [:]   =   [blue, green, red] 
     print   (blue, green, red) 
   
     cv2.destroyAllWindows () 
   
  # Call main ()  
   if   __ name__   =   =   "__ main__"  :  
   main ()