Automating the separation of comic/manga panels into separate files.

How can I take an image like this for example. And automate the process of cropping out each black rectangle and saving it to a separate file?

https://preview.redd.it/dt63l93be5ua1.jpg?width=700&format=pjpg&auto=webp&v=enabled&s=6d41783e2efff85cfef68cb29fe7bb5f0b3ef976

automate computervision example image panels process saving