import numpy as np
import cv2 
img=np.zeros((300,300,3),dtype=np.uint8) 
img[0:100,0:100,0]=255
img[100:200,0:100,0]=77
img[200:300,0:100,0]=99 
img[:100:200,1]=255
img[:,200:300,2]=255
print("img=\n",img)
cv2.imshow("img",img)
cv2.waitKey()
cv2.destroyAllWindows()

