Revise paste ColourPick.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')
cv2.namedWindow('hsv')
cv2.namedWindow('masq')
cap = cv2.VideoCapture(0)

# create trackbars for color change
cv2.createTrackbar('R-low','image',0,255,nothing)
cv2.createTrackbar('R-high','image',255,255,nothing)

cv2.createTrackbar('G-low','image',0,255,nothing)
cv2.createTrackbar('G-high','image',255,255,nothing)

cv2.createTrackbar('B-low','image',0,255,nothing)
cv2.createTrackbar('B-high','image',255,255,nothing)

while(1):
    ret, img = cap.read()
    # Convert BGR to HSV
    hsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)

cv2.imshow('image',img)
    k = cv2.waitKey(1) & 0xFF
    if k == 27:
        break

# get current positions of four trackbars
    rl = cv2.getTrackbarPos('R-low','image')
    rh = cv2.getTrackbarPos('R-high','image')

gl = cv2.getTrackbarPos('G-low','image')
    gh = cv2.getTrackbarPos('G-high','image')
    
    bl = cv2.getTrackbarPos('B-low','image')
    bh = cv2.getTrackbarPos('B-high','image')

lower = np.array([rl,gl,bl])
    upper = np.array([rh,gh,bh])

#    print(rl)

img[:] = [bl,gl,rl]

# Threshold the HSV image to get only certain colors
    mask = cv2.inRange(hsv, lower, upper)    
 
    res = cv2.bitwise_and(img,img, mask= mask)
   
    #cv2.imshow('res',res)
    cv2.imshow('masq',mask)
    cv2.imshow('hsv',hsv)

cv2.destroyAllWindows()