Decode predictor=2 on big-endian TIFFs by swapping to native order#1507
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brendancol merged 1 commit intomainfrom May 7, 2026
Merged
Decode predictor=2 on big-endian TIFFs by swapping to native order#1507brendancol merged 1 commit intomainfrom
brendancol merged 1 commit intomainfrom
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PR #1498 reworked predictor=2 to run sample-wise via a numpy view at the file's byte order. Numba's nopython mode rejects arrays with a non-native byte order, so reading a big-endian TIFF with uint16/uint32/uint64 + predictor=2 raised "Unsupported array dtype: >u2" instead of returning the pixel data. predictor_decode and predictor_encode now byteswap the buffer in place around the kernel call for files whose byte order differs from native. Bytes on the way out stay in the file's order so the downstream chunk.view(file_dtype) step in _decode_strip_or_tile keeps working. uint8 is unaffected (single-byte path skips the view). Tests cover uint16/int16/uint32/int32 round-trips through tifffile-built big-endian predictor=2 files plus a little-endian sanity check.
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Summary
PR #1498 reworked predictor=2 (horizontal differencing) to run sample-wise via a numpy view in the file's byte order. Numba's nopython mode rejects arrays with a non-native byte order, so reading a big-endian TIFF with uint16/uint32/uint64 + predictor=2 raised
TypingError: Unsupported array dtype: >u2instead of returning the pixel data.predictor_decodeandpredictor_encodenow byte-swap the buffer in place around the kernel call when the file byte order differs from native, then swap back so the on-disk representation stays intact for thechunk.view(file_dtype)step in_decode_strip_or_tile. uint8 is unaffected since the single-byte path skips the view.Test plan
test_predictor2_big_endian.pycovers uint16/int16/uint32/int32 round-trips through tifffile-built BE predictor=2 deflate files.test_featuresrecursion issue is unrelated).