In the shell, ImageMagick has this handy ‘identify’ command:

identify  -verbose  some-picture.jpg | grep Interlace

….returns “Interlace: JPEG” if it is progressive,  otherwise it’s a baseline jpeg and it will show: “Interlace: None”

In Python, we can use PIL:

from PIL import Image
'progressive' in Image.open('some-pictures.jpg').info