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Brandon Thomas 71eac70696 Issue #138: DNG: apply the file's own camera-profile look (HueSatMap, LookTable, ToneCurve) 
Lightroom-converted DNGs carry their camera profile's ProfileHueSatMapData1/2
and ProfileLookTableData (and sometimes ProfileToneCurve). We used only the
colour matrices, so such DNGs rendered flat and muted.

- raw: new `profile` module reads the tags (DNG spec ch. 6: value-major,
  hue-middle, saturation-minor tables, wrap-around hue, tri-linear lookups,
  sRGB value encoding) from the raw IFD or IFD 0; malformed tags are ignored.
- engine: the raw loader applies the hue/sat map (interpolated by the same
  illuminant weight as the matrices) before BaselineExposure and the look
  table after it, in linear ProPhoto; a ProfileToneCurve becomes the source's
  camera tone. Without one the standard base tone is kept.
- dngwrite keeps the look with the data (conversions, smart previews, merges).
- Render cache version 7.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
 		2026-10-06 10:36:30 -04:00
..
src Issue #138: DNG: apply the file's own camera-profile look (HueSatMap, LookTable, ToneCurve) 2026-10-06 10:36:30 -04:00
tests M3.1: lightcraft-tiff reader/writer 2026-09-30 11:00:48 -04:00
Cargo.toml M3.1: lightcraft-tiff reader/writer 2026-09-30 11:00:48 -04:00
README.md M3.1: lightcraft-tiff reader/writer 2026-09-30 11:00:48 -04:00

README.md

lightcraft-tiff (L0)

TIFF / IFD reader and writer. Used by lightcraft-raw (DNG, CR2, NEF, ARW…), lightcraft-meta (Exif) and later the TIFF/DNG exporters.

Features

  • Classic TIFF and BigTIFF, little- and big-endian (II/MM). Also accepts the TIFF-like magic numbers of some raw formats (ORF IIRO/IIRS, RW2 IIU) when ParseOptions::accept_raw_magic is set (default).
  • Every field type: BYTE, ASCII, SHORT, LONG, RATIONAL, SBYTE, UNDEFINED, SSHORT, SLONG, SRATIONAL, FLOAT, DOUBLE, IFD, LONG8, SLONG8, IFD8.
  • IFD chain + SubIFDs (330) + Exif (34665) / GPS (34853) / Interoperability (40965) pointer IFDs, resolved into a tree (Ifd::sub_ifds, exif, gps, interop). Entry::offset records the absolute position of each value (needed for maker notes and embedded blobs).
  • parse_ifd_at(data, offset, order, base, bigtiff, opts) parses an IFD whose offsets are relative to an arbitrary base; makernote::parse_makernote knows the header / byte-order / offset-base conventions of Canon, Nikon (types 1 and 3), Sony, Fujifilm, Olympus (old and new), Panasonic and Pentax notes.
  • image::ImageInfo — width/height, bits, samples, compression, photometric, planar config, predictor, sample format and the strip or tile chunk list (chunks(), chunk_bytes()); missing byte counts are inferred.
  • TiffWriter writes IFD chains with strips or tiles, SubIFDs and pointer IFDs, in either byte order, classic or BigTIFF; writer::rational / srational approximate floats as rationals.

Robustness

The reader never panics on malformed input (proptests feed random and mutated files): offsets are bounds-checked; out-of-range or unknown-type entries are skipped; IFD loops are detected; IFD count, nesting depth and entries per IFD are limited; the total bytes of decoded values are capped at 8 × input + 1 MiB so a file cannot make us allocate far more than its own size.

Sources

Public specifications only: TIFF 6.0 (Adobe, 1992), the TIFF 6.0 supplements (IFD type, SubIFDs), the BigTIFF format description (AWare Systems), Adobe DNG Specification 1.7 (tag numbers), CIPA DC-008 Exif 2.32, and the ExifTool tag-name documentation (maker-note header conventions, prose only). No third-party code was consulted.