A CLI to fetch photos and maps from BNF Gallica website.
(sudo) npm install -g git+https://github.com/jonathanlurie/gallica.git
Then, you need the ark ID of the document you want to fetch. You can usually find this ID in the URL.
In a terminal:
gallica --ark btv1b531213318 --save /somepath/image.jpg
It it possible that the document contains more than one image or page, then it is going to be saved as image.0.jpg, image.1.jpg, image.n.jpg. Plus a metadata file will be written under the name image.json.