NIfTI phantoms

In previous versions, MR-zero used ad-hoc formats for its simulation phantoms. It stored the right combination of maps in numpys compressed file format. Starting 2026, we fully switch to a new file format with a precise specification. It is a combination of the widely used NIfTI file format an a JSON configuration file. Exact definitions of the contents of this configuration file makes writing loaders for different applications / programming languages easy. At the same time, care was taken to allow great flexibility and human readability of the files.

You can see the specification here. A closer look at the coordinate system is shown here.

To see how to use phantoms, you can either look at examples or view the API documentation.