This code part i used to change each pixel color to it's nearest main color and give it more cartoon look.But my main intention was to identify dominant primary and secondary colors of those images

ChangeImagePixelColor.py

# import the necessary packages
import numpy as np
import scipy.spatial as sp
import matplotlib.pyplot as plt
import cv2

#Stored all RGB values of main colors in a array
main_colors = [(0,0,0),
                  (255,255,255),
                  (255,0,0),
                  (0,255,0),
                  (0,0,255),
                  (255,255,0),
                  (0,255,255),
                  (255,0,255),
                  ] 

image = cv2.imread("test.jpg")
#convert BGR to RGB image
image = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)

h,w,bpp = np.shape(image)

#Change colors of each pixel
#reference :https://stackoverflow.com/a/48884514/9799700
for py in range(0,h):
    for px in range(0,w):
      ########################
      #Used this part to find nearest color 
      #reference : https://stackoverflow.com/a/22478139/9799700
      input_color = (image[py][px][0],image[py][px][1],image[py][px][2])
      tree = sp.KDTree(main_colors) 
      ditsance, result = tree.query(input_color) 
      nearest_color = main_colors[result]
      ###################
      
      image[py][px][0]=nearest_color[0]
      image[py][px][1]=nearest_color[1]
      image[py][px][2]=nearest_color[2]

# show image
plt.figure()
plt.axis("off")
plt.imshow(image)