How to write a program converting RGB to CMYK in python

rgb_scale = 255

cmyk_scale = 100

def rgb_to_cmyk (r, g, b):

if (r = = 0) and (g = = 0) and (b = = 0):

return 0, 0, 0, cmyk_scale

# rgb [0,255] - > cmy [0,1]

c = 1 - r / float (rgb_scale)

m = 1 - g / float (rgb_scale)

y = 1 - b / float (rgb_scale)

min_cmy = min (c, m, y)

c = (c - min_cmy)

m = (m - min_cmy)

y = (y - min_cmy)

k = min_cmy

return c*cmyk_scale, m*cmyk_scale, y*cmyk_scale, k*cmyk_scale

def cmyk_to_rgb (c, m, y, k):

r = rgb_scale * (1.0 - (c+k) / float (cmyk_scale))

g = rgb_scale * (1.0 - (m+k) / float (cmyk_scale))

b = rgb_scale * (1.0 - (y+k) / float (cmyk_scale))

return r, g, b