{
  "status": "shipping",
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-20",
  "slug": "hdf5-scale-offset",
  "term": "HDF5 scale-offset filter",
  "aliases": [
    "H5Z_FILTER_SCALEOFFSET"
  ],
  "definition": "The HDF5 scale-offset filter reduces per-chunk numeric storage using an offset and a precision setting whose meaning differs between integer and floating-point data.",
  "note": "Integer precision: the parameter selects retained bits; zero requests an automatically selected lossless bit count. Floating-point zero is not a lossless setting, and decimal-place precision is not a significant-digit count. [h5-scale-api]\n\nFill boundary: the HDF Group warns that floating-point values near zero can interact with default fill zero. A h5py 3.15.0 / HDF5 1.14.6 fixture returns 0.009 as zero with scaleoffset=2; moving the sentinel changes which neighborhood is affected. This is a version-scoped observation, not a new vulnerability or incidence estimate. [h5-scale-guide] [hesela-scale]\n\nIntegrity: the high-level h5py API rejects pairing scale-offset and Fletcher32. A diagnostic low-level pipeline can check already transformed bytes without restoring discarded precision; preserve the API guard. NaN and infinities have no preservation guarantee with scale-offset. [h5-scale-guard] [h5-scale-dataset]",
  "related": [
    "hdf5",
    "hdf5-chunked-layout",
    "hdf5-fill-value",
    "checksum"
  ],
  "citations": [
    {
      "id": "h5-scale-api",
      "title": "h5py 3.15.0 create_dataset: scale-offset precision and Fletcher32 restriction",
      "url": "https://github.com/h5py/h5py/blob/3.15.0/h5py/_hl/group.py#L103-L116",
      "accessed": "2026-10-20"
    },
    {
      "id": "h5-scale-guard",
      "title": "h5py 3.15.0 filters.py: high-level scale-offset/Fletcher32 guard",
      "url": "https://github.com/h5py/h5py/blob/3.15.0/h5py/_hl/filters.py#L203-L226",
      "accessed": "2026-10-20"
    },
    {
      "id": "h5-scale-guide",
      "title": "HDF Group dataset guide: scale-offset floating-point suggestions",
      "url": "https://hdfgroup.github.io/hdf5/develop/_h5_d__u_g.html",
      "accessed": "2026-10-20"
    },
    {
      "id": "h5-scale-dataset",
      "title": "h5py 3.15.0 dataset guide: scale-offset, special values and Fletcher32",
      "url": "https://github.com/h5py/h5py/blob/3.15.0/docs/high/dataset.rst",
      "accessed": "2026-10-20"
    },
    {
      "id": "hesela-scale",
      "title": "Hesela: 26 scale-offset round-trip configurations and limits",
      "url": "https://hesela.dev/datasets/hdf5-checksum-coverage/#scale-offset",
      "accessed": "2026-10-20"
    }
  ],
  "advantages": [],
  "limitations": []
}