Turn Scientific Data Formats Into netCDF-Ready Intelligence

The NetCDF Expansion Pack (NEP) extends the netCDF C library with lossless compression filters and User-Defined Format (UDF) readers, so existing C, Fortran, and Python software can read new scientific and imaging formats without code changes.

The Problem

Scientific data is often locked in specialized file formats that require custom parsers, brittle conversion pipelines, and duplicated tooling. Researchers waste time writing format-specific readers instead of doing science.

What NEP Adds to netCDF

NEP builds on two extension points already present in netCDF-C:

  • HDF5 filter plugins for per-variable lossless compression (LZ4 and BZIP2).
  • The NC_Dispatch layer for read-only User-Defined Format (UDF) readers.

Because NEP exposes foreign formats as ordinary netCDF datasets, existing analysis tools, visualization pipelines, and AI/ML workflows can work with DICOM images, protein structures, GRIB2 weather grids, and planetary data without custom parsers. New read-only or read-write readers can be added for additional formats.

NEP is built and maintained by our Senior Engineer, a co-author of the netCDF C/Fortran/C++ libraries and former GRIB/BUFR libraries team lead at NOAA.

Core Capabilities

  • LZ4 compression – high-throughput, near-real-time workflows
  • BZIP2 compression – maximum ratio for long-term archives
  • UDF readers – open DICOM, PDB/mmCIF, GRIB2, GeoTIFF, FITS, CDF, and PDS4 through nc_open()
  • Standard API – no changes to existing C, Fortran, or Python netCDF code
  • CF-style attributes – native metadata translated to netCDF attributes where possible
  • Open source – CMake, Autotools, Spack, and Conda builds available

How NEP Fits Into the netCDF Ecosystem

NEP extends the netCDF C library with User-Defined Format (UDF) readers and additional compression filters, so existing netCDF applications can open new scientific and imaging formats without code changes.

NetCDF C library architecture showing NEP compression filters and UDF readers extending the core netCDF ecosystem

Why NEP?

No Code Changes

Open DICOM, PDB/mmCIF, GRIB2, and other formats through the netCDF API your existing tools already use.

Lossless Compression

LZ4, BZIP2, and LibPressio-integrated filters reduce storage size without losing information.

AI/ML Ready

Feed imaging, weather, and structural-biology data directly into analysis and machine-learning pipelines.

Get Started with NEP

Explore supported formats, see working examples, or reach out for integration support.