[jcupitt]

libvips dev here -- the CLI interface is deliberately really basic, you'll see much better performance and flexibility with one of the language bindings. pyvips works well:

https://github.com/libvips/pyvips

The idea is that complex CLIs like imagemagick's are almost complete programming languages, and need a lot of learning. It's much better (imo) (and less work) to have a good binding, and to lean on python for the programming side.

libvips is mostly self-binding. It has good introspection support, so the core of pyvips is just 200 lines of code, and automatically updates itself for new libvips versions.