Fixel format
The storage of fixel data on disk has been completely overhauled. Rather than the previously used “MRtrix Sparse File / Header (.msf / .msh)” format, fixel data is now represented using standard images stored in a directory that conforms to a newly-defined format. This increases the flexibility of what type of fixel data can be stored, improves the mrview user interface when visualising different parameters within the same set of fixels, and opens the data up for any users / developers who wish to access or manipulate this information directly. The new format is described in more detail in the documentation.
mrview will continue to support the old .msf / .msh format. Additionally, we now provide a new command fixelconvert for converting between the old and new formats.