Dear all,

There doesn't seem to have been much activity here for a while, but I thought it might be worth following up on my earlier post, as I have since had further discussions with colleagues to get an idea of what would be useful in a new file format. On my wish-list would be:

- A mechanism for efficient storage for sparse data (as mentioned previously). Many images are sparse enough that nothing more complex than an option for coordinate/value storage would be needed to improve efficiency significantly.
- The ability to arrange voxel ordering so that spatial dimensions appear last rather than first. This would make voxelwise analysis of multivariate data (fMRI time series, diffusion directions, etc.) much more efficient, particularly for compressed files.
- Simpler conventions for extended metadata and orientation encoding, and fewer data types. Even NIfTI-1 seems more complex than it needs to be, which makes implementation more painful. As far as I know, NIfTI extensions are relatively rarely used (but correct me if I'm wrong!).

I've drafted an illustrative file format proposal at https://github.com/jonclayden/miff, which caters for all of these things, to illustrate further what I mean. Metadata is free-text, with allowance for the use of DICOM tag codes for standard acquisition parameters (TE, TR, etc.).

Incidentally, is there any further news on NIfTI-2? Can we follow the state of things anywhere?

All the best,
Jon