HDF5 Data Viewer
================

The HDF5 viewer opens a projection HDF5 file, shows any image slice
(optionally divided by the white field with pixel-shift alignment),
and lists the full metadata tree. Useful for sanity-checking a raw
dataset before spending GPU time on it.

.. figure:: /_static/screenshots/hdf5_viewer_overview.png
   :alt: HDF5 Viewer
   :align: center

Opening a file
--------------

In the Batch table, right-click a row → *View Data* (or the *View
Data* button). The viewer opens in a separate window for that file.

Image tab
---------

- **Normalization** — toggle ``data / data_white``
- **Slider** — pick the projection index
- **Contrast** — Per Image / Min-Max / percentile modes (1–99, 2–98,
  5–95) / Manual
- **Shift** — arrow keys nudge the white field by 1 px (Shift +1 → 10
  px, Ctrl → 50 px). Useful for checking flat-field alignment.
- **Statistics** — min / max / mean / std of the current slice.

Metadata tab
------------

- **Attributes** — searchable table of every HDF5 attribute with its
  value and dtype. CSV export.
- **File structure** — tree of groups and datasets with shapes /
  dtypes.

Expected structure
------------------

::

   /exchange/data         3D projection stack (required)
   /exchange/data_white   3D white field stack  (required for normalisation)

Additional groups under ``/process``, ``/measurement``, ``/instrument``
are displayed but not required.

Common failures
---------------

File won't open
   Check ``ls -la`` and ``h5ls`` on the file. Usually permissions or
   an in-progress write.

Missing ``/exchange/data`` or ``data_white``
   Not a standard tomography HDF5 layout. Look in the Metadata tab for
   the actual dataset names.

Slow to navigate
   Some datasets have uncompressed per-projection chunks that force a
   full re-read for every slide. Try the viewer on a binned copy.

See Also
--------

- :doc:`batch_tab`
- :doc:`main_tab`
- :doc:`../user_guide/reconstruction`
- :doc:`../advanced/troubleshooting`