import sys
import struct

import time
s = time.time()
with open(sys.argv[1], 'rb') as f:
    data = f.read()

r, g, b = 0, 0, 0
r, g, b = 1, 1, 1
w=4192
h=3104

pixels = struct.unpack("<%dH" % (w*h), data)
d = time.time()
for i in range(h):
    if i % 2 == 0:
        r += sum(pixels[i*w:(i+1)*w:2])
        g += sum(pixels[i*w+1:(i+1)*w+1:2])
    else:
        g += sum(pixels[i*w:(i+1)*w:2])
        b += sum(pixels[i*w+1:(i+1)*w+1:2])


r=r/w/h*4
g=g/w/h*2
b=b/w/h*4
m=(r+g+b)/3
e = time.time()
print('\rR', round(r, 2), round(m/r, 3), round(g/r, 3))
print('G', round(g, 2), round(m/g, 3), '1.000')
print('B', round(b, 2), round(m/b, 3), round(g/b, 3))
print("total time: %.3f seconds. Data read/prepare: %.3f" % ((e - s), (d - s)))