[NXtomo] Need user flags

[vasole]

The NXtomo definition foresees three flags in the image_key dataset (projection = 0, flat field = 1, dark field = 2, invalid = 3). We need to add some additional keys to indicate other uses (for instance control images).

When dealing with detectors, the possibility to use user_defined masks was foreseen but it is not the case for this definition. We would not like to take a number that later on is used by NeXus. Because of that we have started to use negative numbers to indicate user specific meaning. Could that approach (flags smaller than 0 are available for the user) be officially endorsed or an alternative suggested?

[vasole]

By an alternative I mean things like flags bigger than XX are free for the user.

[mkoennecke]

Armando, Am 05.03.2020 um 09:03 schrieb V. Armando Solé <[email protected]<mailto:[email protected]>>: The NXtomo definition foresees three flags in the image_key dataset (projection = 0, flat field = 1, dark field = 2, invalid = 3). We need to add some additional keys to indicate other uses (for instance control images). When dealing with detectors, the possibility to use user_defined masks was foreseen but it is not the case for this definition. We would not like to take a number that later on is used by NeXus. Because of that we have started to use negative numbers to indicate user specific meaning. Could that approach (flags smaller than 0 are available for the user) be officially endorsed or an alternative suggested? This could be done but needs some more opinions from NIAC. But I would rather prefer to give more numbers in image_key meaning. Especially when these additional image keys are of general interest. Regards, Mark Koennecke — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub<#762?email_source=notifications&email_token=ABGL7WTTBGBK5D4IUH7FQILRF5MDLA5CNFSM4LCECJP2YY3PNVWWK3TUL52HS4DFUVEXG43VMWVGG33NNVSW45C7NFSM4ISWBCQA>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ABGL7WWV3BQPZKBPXBP7FHLRF5MDLANCNFSM4LCECJPQ>.

[vasole]

If to add control frames is a common practice, then I agree it would be best to add an additional number.

[benajamin]

This was discussed in the April 2020 telco. We agreed that reserving negative image keys for user-defined cases is a good strategy, but there should also be additional fields (perhaps in a groups to collect them together) to provide a standardised method to record the meaning of these keys. An example could be:
user_keys:NXgroup
minus_1: NXnote - "timing control"
minus_2:NXnote - "laser pulse"

We recommend writing a NIAC proposal for amending the NXtomo application definition in such a manner.