3.1 Axes metadata

[dstansby]

"axes" describes the dimensions of a physical coordinate space. It is a list of dictionaries, where each dictionary describes a dimension (axis) and:

• MUST contain the field "name" that gives the name for this dimension. The values MUST be unique across all "name" fields.

• SHOULD contain the field "type". It SHOULD be one of "space", "time" or "channel", but MAY take other string values for custom axis types that are not part of this specification yet.

• SHOULD contain the field "unit" to specify the physical unit of this dimension. The value SHOULD be one of the following strings, which are valid units according to UDUNITS-2.

    Units for "space" axes: angstrom, attometer, centimeter, decimeter, exameter, femtometer, foot, gigameter, hectometer, inch, kilometer, megameter, meter, micrometer, mile, millimeter, nanometer, parsec, petameter, picometer, terameter, yard, yoctometer, yottameter, zeptometer, zettameter
  
    Units for "time" axes: attosecond, centisecond, day, decisecond, exasecond, femtosecond, gigasecond, hectosecond, hour, kilosecond, megasecond, microsecond, millisecond, minute, nanosecond, petasecond, picosecond, second, terasecond, yoctosecond, yottasecond, zeptosecond, zettasecond
  

If part of § 3.4 "multiscales" metadata, the length of "axes" MUST be equal to the number of dimensions of the arrays that contain the image data.

https://ngff.openmicroscopy.org/0.4/index.html#axes-md

[dstansby]

I think a combination of #43 and #42 fixes this 🎉