Python provides various method to download image but it works as per your python version. but before downloading image it is best to download image in specific folder. this will be more organized way to allocate resource.
for example
For python v3
import urllib.request
import os
prodimg="http://someimg.com/somg-img.png"
sku="img1"
directory="smartphone\\"+sku
if not os.path.exists(directory):
os.makedirs(directory)
urllib.request.urlretrieve(prodimg, directory+'\\'+sku+'.jpg')
For python v2
import urllib
import os
directory="smartphone"
prodimg="img1"
if not os.path.exists(directory):
os.makedirs(directory)
f = open(directory+'\\'+prodimg+'.jpg','wb')
f.write(urllib.urlopen('http://www.gunnerkrigg.com//comics/00000001.jpg').read())
f.close()