from matplotlib import pyplot as plt
img = plt.imread( 'messi5.jpg' )

# split the image into 3 channel data
red  = img[:, :, 0]  # blue channel data
green = img[:, :, 1]  # green channel data
blue   = img[:, :, 2]  # red channel data

fusion1 = blue/3 + green/3 + red/3
print( "fustion1.dtype = ", fusion1.dtype ) 

plt.imshow( fusion1, cmap='gray' ) 
plt.show()

import numpy as np
from matplotlib import pyplot as plt
img = plt.imread( 'messi5.jpg' )

# split the image into 3 channel data
red  = img[:, :, 0]  # blue channel data
green = img[:, :, 1]  # green channel data
blue   = img[:, :, 2]  # red channel data

fusion2 = (blue + green + red)/3 # overflow 발생 => 에러 
print( "fustion2.dtype = ", fusion2.dtype )

plt.imshow( fusion2 , cmap='gray' )
plt.show()