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M3.7: header probe agrees with decode on subsampled lossless JPEG; lossless ARW corpus samples 

- tiffraw: Mode::Header parses the first LJ92 frame header (Compression 7),
  so probe_info reports Unsupported for subsampled frames (Sony lossless
  M/S) as the full decode does, instead of claiming the file decodes.
- corpus: CC0 ILCE-7M4 lossless L/M/S samples from raw.pixls.us in
  `cargo xtask corpus`; M/S listed as known unsupported.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
Brandon Thomas 2026-10-04 01:21:33 -04:00
parent 2956f97352
commit d6eac6685c
3 changed files with 13 additions and 0 deletions
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7
crates/raw/src/tiffraw.rs
View File

@ -60,6 +60,13 @@ pub(crate) fn read_image_in(mode: crate::Mode, data: &[u8], info: &ImageInfo, or
crate::Mode::Full => read_image(data, info, order, packing),
crate::Mode::Header => {
check_image(data, info)?;
// a lossless-JPEG layout the decoder rejects (subsampled components, e.g. Sony's
// lossless M/S sizes) must fail here too, as the full decode will
if info.compression == 7
&& let Some(src) = info.chunks(data.len() as u64).first().and_then(|c| chunk_bytes(data, c))
{
ljpeg::frame_info(src)?;
}
Ok(if info.sample_format == 3 { RawData::F32(Vec::new()) } else { RawData::U16(Vec::new()) })
}
}

2
crates/raw/tests/corpus.rs
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@ -16,6 +16,8 @@ fn corpus_root() -> PathBuf {
/// Variants known not to decode yet (see the crate docs): matched against the lower-case file name.
const KNOWN_UNSUPPORTED: &[&str] = &[
"cr3-", // CR3 / CRX (M11.1)
"arw-sony-a7m4-lossless-m", // Sony lossless compressed M/S: subsampled (YCbCr) lossless JPEG
"arw-sony-a7m4-lossless-s", // "
"raf-fuji-xt20-compressed", // Fujifilm compressed RAF
"rw2-panasonic-gh5.", // Panasonic raw format 4 (quantised)
"rw2-panasonic-gx80", // "

4
xtask/src/main.rs
View File

@ -230,6 +230,10 @@ const RAW_SAMPLES: &[(&str, &str)] = &[
"https://raw.pixls.us/getfile.php/2418/nice/Sony%20-%20ILCE-7M3%20-%2014bit%2014bit%20uncompressed%20%283:2%29.ARW",
),
("arw-sony-a7m4-14bit.arw", "https://raw.pixls.us/getfile.php/6936/nice/Sony%20-%20ILCE-7M4%20-%2014bit%20%283:2%29.ARW"),
// lossless compressed (Compression 7): L is 2×2 CFA cells per LJ92 sample; M and S are subsampled
("arw-sony-a7m4-lossless-l.arw", "https://raw.pixls.us/data/Sony/ILCE-7M4/ILCE-7M4_DSC06674_FullFrame-LossLess-Compressed-Large.ARW"),
("arw-sony-a7m4-lossless-m.arw", "https://raw.pixls.us/data/Sony/ILCE-7M4/ILCE-7M4_DSC06675_FullFrame-LossLess-Compressed-Medium.ARW"),
("arw-sony-a7m4-lossless-s.arw", "https://raw.pixls.us/data/Sony/ILCE-7M4/ILCE-7M4_DSC06676_FullFrame-LossLess-Compressed-Small.ARW"),
("cr2-canon-5d3-sraw2.cr2", "https://raw.pixls.us/getfile.php/773/nice/Canon%20-%20EOS%205D%20Mark%20III%20-%20sRAW2%20%28sRAW%29.CR2"),
("cr2-canon-5d3.cr2", "https://raw.pixls.us/getfile.php/771/nice/Canon%20-%20EOS%205D%20Mark%20III.CR2"),
("cr2-canon-80d.cr2", "https://raw.pixls.us/getfile.php/1294/nice/Canon%20-%20EOS%2080D%20-%20RAW%20%283:2%29.CR2"),