[jira] [Created] (TIKA-4861) Content-based detection for TIFF-based raw camera formats (NEF, PEF, ARW, DNG, SRW) and for RAF, RW2 and MRW

["Dominik Schmidt (Jira)" <ji...@apache.org>]

Dominik Schmidt created TIKA-4861:
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             Summary:  Content-based detection for TIFF-based raw camera formats (NEF, PEF, ARW, DNG, SRW) and for RAF, RW2 and MRW
                 Key: TIKA-4861
                 URL: https://issues.apache.org/jira/browse/TIKA-4861
             Project: Tika
          Issue Type: Improvement
            Reporter: Dominik Schmidt


Most raw camera formats are still detected by file extension only. Without a name, a stream is detected as image/tiff (or application/octet-stream for the non-TIFF ones), parsed by the generic TIFF parser, and the previews RawTiffParser emits as THUMBNAIL embedded documents (TIKA-4824, TIKA-4851) are never seen. Clients that upload without a reliable file name, such as tika-server callers sending a bare body, get no thumbnail for these files.

Two groups:

1. Formats with a fixed signature that tika-mimetypes.xml does not match yet: Fuji RAF starts with "FUJIFILMCCD-RAW", Panasonic RW2 with "IIU\0" (a TIFF variant with its own magic number 0x55), Minolta MRW with "\0MRM"; Olympus ORF also occurs big-endian as "MMOR" and as "IIRS" next to the "IIRO" we match. These are magic entries only. Canon CR2/CR3 already have theirs (TIKA-3991).
2. Formats that are valid TIFF files: Nikon NEF/NRW, Pentax PEF/PTX, Sony ARW/SRF/SR2, Samsung SRW and Adobe DNG. No fixed-offset magic can tell them from a plain TIFF, and the Make tag alone is not enough: Nikon and Pentax cameras also write real TIFFs with their name in Make. ExifTool identifies these by content in two steps: a DNGVersion tag (0xC612) means DNG, and a vendor-specific Compression value (0x0103) in any IFD names the format (34713 NEF, 32767 ARW, 65535 PEF, 32770 SRW). That misses uncompressed raws (Compression 1), which can be caught by the image data itself: a raw holds an image with PhotometricInterpretation 32803 (CFA) or 34892 (LinearRaw) in IFD0 or a SubIFD (0x014A), where a plain TIFF has 2 (RGB); there Make picks the vendor. 
Proposal: a Detector in tika-parser-image-module, registered via SPI, that only acts when the TIFF magic matches and reads the IFD chain and SubIFDs with a bounded reader (the one in RawTiffParser already handles classic TIFF and BigTIFF), applying those rules in that order and returning application/octet-stream otherwise so image/tiff stands. A caller-supplied type or file name keeps precedence as usual.

Both parts can go into one PR; the second is where the review effort is.



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