title: How to download image from site with no clear extention?
body: <p>I am trying to download an image from the NGA.gov site using python 3 and urllib.</p>
  
  <p>The site does not display images in a standard .jpg fashion and i get an error.</p>
  
  <pre><code>import urllib.request
  from bs4 import BeautifulSoup
  
  
  try:
      with urllib.request.urlopen("http://images.nga.gov/?service=asset&amp;action=show_preview&amp;asset=33643") as url:
          s = url.read()
  
      soup = BeautifulSoup(s, 'html.parser') 
  
  
      img = soup.find("img")
      urllib.request.urlretrieve(img,"C:\art.jpg")
  
  except Exception as e:
      print (e)
  </code></pre>
  
  <p>Error:
  Some characters could not be decoded, and were replaced with REPLACEMENT CHARACTER.
  expected string or bytes-like object</p>
  
  <p>Can someone please why i am getting this error and how to get the images to my computer. </p>