import os.path
import requests
import re
img_link = 'http://mirsofta.ru/screen/3493841820.png'
p = requests.get(img_link)
folder_name = 'img'
if not os.path.isdir(folder_name):
    os.makedirs(folder_name)
img_name = re.sub('^.*/', '', img_link)
with open(os.path.join(folder_name, img_name), 'wb') as out:
    out.write(p.content)