Get the dimensions of a remote image... fast.

fast-dims.py

import asyncio

import aiohttp

# I'm importing Pillow-SIMD for increased performance, but you can use ordinary Pillow if you wish.
from PIL import ImageFile

# The remote image we'll be finding the dimensions for.
SOURCE = "http://rustacean.net/assets/rustacean-orig-noshadow.png"

async def main():
    # Start HTTP client.
    async with aiohttp.ClientSession(raise_for_status=True) as session:
        print(await get_dimensions(session, SOURCE))

async def get_dimensions(session, image) -> (int, int):
    async with session.get(image) as req:
        parser = ImageFile.Parser()

        # If an image can't be parsed, read 64 bytes more from the response.
        # Will throw an exception if it reaches the end of the response body and can't parse an image.
        # Be sure to handle this exception in production code.
        while not parser.image:
            parser.feed(await req.content.readexactly(64))

        return parser.image.size

loop = asyncio.get_event_loop()
loop.run_until_complete(main())