Dominik Schmidt created TIKA-4851:
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Summary: RawTiffParser: mark only the largest JPEG preview as
THUMBNAIL
Key: TIKA-4851
URL: https://issues.apache.org/jira/browse/TIKA-4851
Project: Tika
Issue Type: New Feature
Reporter: Dominik Schmidt
RawTiffParser (TIKA-4824) emits every JPEG preview found in the IFD chain and
SubIFDs as an embedded document with tk:embedded-resource-type=THUMBNAIL, in
IFD walk order. A NEF typically carries a 160x120 thumbnail in IFD0 and a
full-size preview in a SubIFD, DNG and CR2 similar, so the first THUMBNAIL is
usually the smallest one. A client that wants the representative image has to
parse the dimensions of every preview and pick the largest, which is a
format-specific special case again; every other parser that emits THUMBNAIL
emits exactly one.
Proposal:
- Only the largest preview (by JPEG byte length, or by the IFD's
ImageWidth/ImageLength when present) is marked THUMBNAIL and emitted first.
- The remaining previews are still extracted, marked INLINE (they are
renderings of the same image, not attachments), keeping the current thumbnail_N
generated names or switching the smaller ones to an image_N prefix.
Motivation for both tickets: a generic "first THUMBNAIL is the preview" rule
across all formats in a downstream consumer (OpenCloud's Tika extractor).
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