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Metadata Support Matrix (Draft)

This document summarizes the current read-path coverage in OpenMeta.

It is meant to answer four basic questions:

  • which containers are scanned
  • which metadata families are decoded into MetaStore
  • where display-name mapping exists
  • what can be dumped or exported today

Status Labels

  • Yes: supported in current code
  • Partial: supported, but still bounded or best-effort
  • No: not supported yet

Coverage Snapshot

Current tracked-gate status:

  • EXIF tag-id compare gates are passing on tracked HEIC/HEIF, CR3, and mixed RAW corpora.
  • EXR header metadata compare is passing for the documented name/type/value-class contract.
  • Sidecar export paths (lossless and portable) are covered by baseline and smoke tests.
  • MakerNote coverage is tracked by baseline gates with broad vendor support; unknown vendor tags are preserved as raw metadata for lossless workflows.
  • BMFF edge-path tests include iloc construction-method-2 relation variants and safe-skip handling for invalid references.

Container Coverage

Container / input type Block discovery Structured decode in simple_meta_read(...) Notes
JPEG Yes Yes EXIF, XMP, extended XMP, ICC, MPF, Photoshop IRB, comments, vendor APP blocks, and bounded JUMBF/C2PA
PNG Yes Yes EXIF, XMP, ICC, structured PNG text, and bounded JUMBF/C2PA
WebP Yes Yes EXIF, XMP, ICC, and bounded JUMBF/C2PA
GIF Yes Partial XMP, ICC, and structured comments
TIFF / DNG / TIFF-based RAW Yes Yes EXIF, MakerNote, XMP, IPTC, Photoshop IRB, ICC, GeoTIFF, and bounded JUMBF/C2PA
CRW / CIFF Yes Partial Derived EXIF bridge plus bounded native Canon CIFF naming and projection
RAF / X3F Partial Partial Mainly embedded-TIFF follow path with best-effort extras
JP2 Yes Yes EXIF, XMP, IPTC, ICC, and GeoTIFF
JXL Yes Yes EXIF, XMP, and bounded JUMBF/C2PA; supported brob wrapped metadata is decoded
HEIF / AVIF / CR3 Yes Partial EXIF, XMP, ICC, CR3 maker blocks, BMFF derived fields, and bounded JUMBF/C2PA
EXR n/a via scan_auto(...) Yes Header attributes only; no pixel decode

Metadata Family Coverage

Metadata family Decode Name mapping Dump / export Notes
EXIF (MetaKeyKind::ExifTag) Yes Yes Yes Standard EXIF plus pointer IFDs
MakerNote Partial / Yes Partial / Yes Lossless yes; portable limited Broad vendor coverage; unknown tags may remain raw
XMP (MetaKeyKind::XmpProperty) Yes Native schema/path Yes Requires Expat at build time
ICC (IccHeaderField, IccTag) Yes Yes Yes Header fields plus tag table; raw tag payload preserved
IPTC-IIM (IptcDataset) Yes Yes Yes Raw dataset bytes preserved
Photoshop IRB (PhotoshopIrb) Yes Partial / Yes Yes Raw resources preserved plus a bounded interpreted subset
MPF Yes Yes Yes Basic TIFF-IFD decode
GeoTIFF (GeotiffKey) Yes Yes Yes GeoKeyDirectoryTag decode
BMFF derived fields (BmffField) Yes Yes Yes ftyp, item-info, iref, graph summaries, aux semantics, and bounded primary-linked image roles
JUMBF / C2PA (JumbfField, JumbfCborKey) Partial Yes Yes Draft structural and semantic layer; not full conformance
EXR attributes (ExrAttribute) Yes Native names Yes Header attributes only

Important Bounded Areas

CRW / CIFF

OpenMeta now does more than a pure derived-EXIF bridge:

  • common native CIFF tags are named
  • a bounded set of native subtables is projected
  • stable scalar native CIFF fields are decoded where the layout is clear

It is still a partial lane compared to the deepest legacy Canon tooling.

Photoshop IRB

OpenMeta preserves raw IRB resources and also decodes a bounded interpreted subset. That subset includes common fixed-layout resources such as:

  • ResolutionInfo
  • VersionInfo
  • PrintFlags
  • JPEG_Quality
  • PrintScaleInfo
  • PixelInfo
  • ChannelOptions
  • PrintFlagsInfo
  • ClippingPathName

This is useful, but it is still not full Photoshop-resource parity.

BMFF (HEIF / AVIF / CR3)

OpenMeta now has a bounded semantic model on top of raw item discovery:

  • ftyp.*
  • primary item properties
  • iinf/infe item-info rows
  • typed iref.<type>.* rows
  • graph summaries
  • auxC-typed auxiliary semantics
  • bounded primary-linked image-role fields

This is intentionally smaller than a full QuickTime/BMFF semantic model.

JXL

OpenMeta decodes:

  • direct Exif
  • direct xml
  • direct jumb
  • direct c2pa
  • wrapped brob forms for those same realtypes

Other brob realtypes are still out of scope.

JUMBF / C2PA

Current support is intentionally draft:

  • structural BMFF box decode
  • bounded CBOR traversal
  • draft c2pa.semantic.* projection
  • draft verify scaffolding

What this means in practice:

  • OpenMeta can expose useful manifest / claim / signature / ingredient shape information
  • OpenMeta does not yet claim full C2PA manifest semantics, trust semantics, or full policy validation

Tool-Level Behavior

Tool Purpose Current state
metaread Human-readable metadata listing Shows decoded entries with mapped names where available
metavalidate Metadata validation Reports decode-status and validation issues with machine-readable issue codes
metadump Sidecar and preview dump tool Supports lossless and portable sidecar output plus preview extraction
thumdump Preview extractor Extracts embedded preview candidates
metatransfer Transfer/edit smoke tool Exercises the transfer core for supported target families

Main Current Gaps

  • HEIF/AVIF scene semantics beyond the current bounded primary-linked role surface
  • additional JXL brob realtypes beyond Exif, xml , jumb, and c2pa
  • full JUMBF/C2PA semantics and policy validation
  • deeper RAF / X3F native semantics beyond embedded-TIFF follow paths
  • broader Photoshop IRB interpretation beyond the current bounded subset

Related Docs