There are 2 main ways:

1. Using .content (simplest/official) (see Zhenyi Zhang's answer):

   import io  # Note: io.BytesIO is StringIO.StringIO on Python2.
   import requests
   
   r = requests.get('http://lorempixel.com/400/200')
   r.raise_for_status()
   with io.BytesIO(r.content) as f:
       with Image.open(f) as img:
           img.show()
   

2. Using .raw (see Martijn Pieters's answer):

   import requests
   
   r = requests.get('http://lorempixel.com/400/200', stream=True)
   r.raise_for_status()
   r.raw.decode_content = True  # Required to decompress gzip/deflate compressed responses.
   with PIL.Image.open(r.raw) as img:
       img.show()
   r.close()  # Safety when stream=True ensure the connection is released.
   

Timing both shows no noticeable difference.

There are 2 main ways:

1. Using .content (simplest/official) (see Zhenyi Zhang's answer):

   import io  # Note: io.BytesIO is StringIO.StringIO on Python2.
   import requests
   
   r = requests.get('http://lorempixel.com/400/200')
   r.raise_for_status()
   with io.BytesIO(r.content) as f:
       with Image.open(f) as img:
           img.show()
   

2. Using .raw (see Martijn Pieters's answer):

   import requests
   
   r = requests.get('http://lorempixel.com/400/200', stream=True)
   r.raise_for_status()
   r.raw.decode_content = True  # Required to decompress gzip/deflate compressed responses.
   with PIL.Image.open(r.raw) as img:
       img.show()
   r.close()  # Safety when stream=True ensure the connection is released.
   

Timing both shows no noticeable difference.

There are 2 main ways:

1. Using .content (simplest/official) (see Zhenyi Zhang's answer):

   import io  # Note: io.BytesIO is StringIO.StringIO on Python2.
   import requests
   
   r = requests.get('http://lorempixel.com/400/200')
   r.raise_for_status()
   with io.BytesIO(r.content) as f:
       with Image.open(f) as img:
           img.show()
   

2. Using .raw (see Martijn Pieters's answer):

   import requests
   
   r = requests.get('http://lorempixel.com/400/200', stream=True)
   r.raise_for_status()
   r.raw.decode_content = True  # Required to decompress gzip/deflate compressed responses.
   with PIL.Image.open(r.raw) as img:
       img.show()
   

Timing both shows no noticeable difference.

There are 2 main ways:

1. Using .content (simplest/official) (see Zhenyi Zhang's answer):

   import io  # Note: io.BytesIO is StringIO.StringIO on Python2.
   import requests
   
   r = requests.get('http://lorempixel.com/400/200')
   r.raise_for_status()
   with io.BytesIO(r.content) as f:
       with Image.open(f) as img:
           img.show()
   

2. Using .raw (see Martijn Pieters's answer):

   import requests
   
   r = requests.get('http://lorempixel.com/400/200', stream=True)
   r.raise_for_status()
   r.raw.decode_content = True  # Required to decompress gzip/deflate compressed responses.
   with PIL.Image.open(r.raw) as img:
       img.show()
   r.close()  # Safety when stream=True ensure the connection is released.
   

Timing both shows no noticeable difference.