Only write supported unit names, especially avoid non UTF-8 characters

[constantinpape]

It would be good to only write unit names that are recommended in the v0.4 spec, see https://github.com/ome/ngff/blob/main/0.4/index.bs#L228-L229.

I understand that this is a bit tricky, since the unit names are read from the image metadata in Fiji, but we can add a dict with common translations and then throw a warning if no match is found.

It would be especially important to write micrometer instead of $\mu$m, to stick with simple string encoding; this otherwise might break implementations that only support utf-8.

(There might be an issue on this topic already, but I couldn't find it.)

[K-Meech]

I'll look into this - link this issue: mobie/mobie-viewer-fiji#583
How do you handle this in the python library? Do you only accept the specific 0.4 strings? Also, do you specify a certain unit to use for the whole project? At the moment, I don't constrain this at all, so the project could be all in nanometer, all in micrometer etc...

[constantinpape]

I'll look into this - link this issue: mobie/mobie-viewer-fiji#583

Thanks for linking the issue.

How do you handle this in the python library? Do you only accept the specific 0.4 strings?

Right now I am also not handling this at all in python, I made an issue to keep track of this: mobie/mobie-utils-python#41 and I will try to use functionality from ome-zarr-py / maybe contribute it myself.
(But the plan is to only allow units in the v0.4 spec.)

Also, do you specify a certain unit to use for the whole project? At the moment, I don't constrain this at all, so the project could be all in nanometer, all in micrometer etc...

Yes, I also do not constrain this right now. It would indeed be good to think about this, I am not sure what's the best approach right now...

[constantinpape]

I think this is implemented already, correct @K-Meech?

[K-Meech]

Yes - this is done already. If possible, it converts the unit to one of the approved OME-ZARR units.