[NeXus-definitions-tickets] [NeXusDefinitions] #130: proposal for image_exchange format

[NeXus Base Classes and Instrument Definitions]

#130: proposal for image_exchange format
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  Reporter:  Pete Jemian  |       Owner:  Pete Jemian
      Type:  task         |      Status:  reopened   
  Priority:  minor        |   Milestone:             
Resolution:               |    Keywords:             
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Changes (by Pete Jemian):

  * status:  closed => reopened
  * resolution:  fixed =>


Old description:

> Chris Jacobsen, APS, has proposed a simplified plan to store images in
> HDF5 files for exchange amongst experimenters.  Express that plan in NXDL
> as an {{{NXnote}}}, following all the rules of the schema, and see if
> that community is receptive to a NeXus description of their plans.
> Perhaps they could become interested in classifying their various
> metadata using standard NeXus base classes such as {{{NXuser}}},
> {{{NXsample}}}, {{{NXinstrument}}}, ...

New description:

 Chris Jacobsen, APS, has proposed a simplified plan to store images in
 HDF5 files for exchange amongst experimenters.  Express that plan in NXDL
 as an {{{NXnote}}}, following all the rules of the schema, and see if that
 community is receptive to a NeXus description of their plans.  Perhaps
 they could become interested in classifying their various metadata using
 standard NeXus base classes such as {{{NXuser}}}, {{{NXsample}}},
 {{{NXinstrument}}}, ...

 The basic proposition is to establish a simple standard for exchange of
 imaging data.

  * Required:
   * Image set (1D, 2D, 3D, 4D, …)
   * Rank and Dimensions of image set
  * Optional additional information to be stored:
   * Version
   * Complex_index
   * Image type
   * Positions (independent axes): values, dimensions, names, units
   * Timestamp for image set
   * Specimen names and related info
   * Instrument names and related info
   * Data acquisition system and related info
   * Processing steps and related info
   * Experimenter names and related info
   * Comments

 Note that {{{complex_index}}} describes if the image set values are real
 or complex.  It was described as:
 ''this is an integer that, if present, tells what dimension holds
 {real,imaginary} pairs for complex numbers (dimensioning is assumed to
 start at 0).  If absent, or if <0 or >(n_dimensions-1), it is assumed that
 the array is pure real. For a 640x480 complex array, one might have
 n_dimensions=3, complex_index=0, and dimensions[]=[2,640,480].''

--

Comment:

 need to revise the NXDL to be more like other NeXus application
 definitions.  This easily fits the notion of a NeXus application
 definition used as a child of {{{NXentry}}} (thus a {{{NXsubentry}}}).

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Ticket URL: <http://trac.nexusformat.org/definitions/ticket/130#comment:6>
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NeXus Base Classes and Instrument Definitions