Pillow

Pillow is the actively maintained fork of the long-abandoned Python Imaging Library (PIL), and remains the standard way to work with images in Python — resizing, cropping, format conversion, filters, and basic drawing operations, all through a straightforward API.

It underpins a huge share of the Python ecosystem’s image handling indirectly: web frameworks generating thumbnails, data pipelines preprocessing images for ML models, and reporting tools that need to embed charts or photos in generated documents all tend to lean on Pillow somewhere in the chain.