SLZ Data Format

The Scyllarus Library ZIP (SLZ) file format is a comprehensive format for spectral libraries, based on the HDF5 file structure.


  • Compressed – storing library spectra using the compression built in to HDF5.
  • Transportable – the HDF5 format can be read on a variety of platforms, including Windows, Linux and Mac, and by a variety of different software packages;
  • Comprehensive – storing the Scyllarus processed Reflectance, Highlight and Shading layers along with the material analysis results;
  • Suitable for Research – the Scyllarus MATLAB® Toolbox can read and write this format.

How it works

SLZ files have a structure based upon two fields. These are

  • HDR: A field containing ENVI compatible header fields and other tags specific to the SLZ structure.
  • Endmembers: An array containing the library spectra. For the sake of fidelity, this array is always stored as raw values.

Each of the above elements is stored within the hierarchical SLZ file, as its own field. The tool ‘HDF View‘ allows you to inspect a SLZ file and view its contents as raw data.

More Information

You can download the detailed HSZ format specification document here.