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https://issues.apache.org/jira/browse/TIKA-4851?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tilman Hausherr updated TIKA-4851:
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Fix Version/s: 4.1.0
> 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
> Priority: Major
> Fix For: 4.1.0
>
>
> 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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