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Read Short as u16, SignedShort as i16 #235

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5808cd0
Add TiffFormatError::ShortExpected enum variant
weiji14 Jul 22, 2024
36f8ee0
Cast Short to u16 instead of u32
weiji14 Jul 22, 2024
1e3bcf2
Cast SignedShort to i16 instead of i32
weiji14 Jul 22, 2024
1a07958
Merge branch 'master' into short_u16
weiji14 Mar 16, 2025
fc4cded
Fix encode_decode tests returning Short instead of Unsigned for some …
weiji14 Mar 16, 2025
5f7c894
Raise TiffFormatError:ShortExpected in into_u16_vec
weiji14 May 5, 2025
c87979b
More proper Short/SignedShort outputs for reading tags (case 4)
weiji14 May 7, 2025
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20 changes: 9 additions & 11 deletions src/decoder/ifd.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -59,9 +59,7 @@ impl Value {
Short(val) => Ok(val),
Unsigned(val) => Ok(u16::try_from(val)?),
UnsignedBig(val) => Ok(u16::try_from(val)?),
val => Err(TiffError::FormatError(
TiffFormatError::UnsignedIntegerExpected(val),
)),
val => Err(TiffError::FormatError(TiffFormatError::ShortExpected(val))),
}
}

Expand Down Expand Up @@ -163,6 +161,7 @@ impl Value {
}
Ok(new_vec)
}
Short(val) => Ok(vec![val.into()]),
Unsigned(val) => Ok(vec![val]),
UnsignedBig(val) => Ok(vec![u32::try_from(val)?]),
Rational(numerator, denominator) => Ok(vec![numerator, denominator]),
Expand Down Expand Up @@ -205,9 +204,7 @@ impl Value {
Ok(new_vec)
}
Short(val) => Ok(vec![val]),
val => Err(TiffError::FormatError(
TiffFormatError::UnsignedIntegerExpected(val),
)),
val => Err(TiffError::FormatError(TiffFormatError::ShortExpected(val))),
}
}

Expand Down Expand Up @@ -285,6 +282,7 @@ impl Value {
}
Ok(new_vec)
}
Short(val) => Ok(vec![val.into()]),
Unsigned(val) => Ok(vec![val.into()]),
UnsignedBig(val) => Ok(vec![val]),
Rational(numerator, denominator) => Ok(vec![numerator.into(), denominator.into()]),
Expand Down Expand Up @@ -433,8 +431,8 @@ impl Entry {
Type::BYTE => Unsigned(u32::from(self.offset[0])),
Type::SBYTE => Signed(i32::from(self.offset[0] as i8)),
Type::UNDEFINED => Byte(self.offset[0]),
Type::SHORT => Unsigned(u32::from(self.r(bo).read_u16()?)),
Type::SSHORT => Signed(i32::from(self.r(bo).read_i16()?)),
Type::SHORT => Short(self.r(bo).read_u16()?),
Type::SSHORT => SignedShort(self.r(bo).read_i16()?),
Type::LONG => Unsigned(self.r(bo).read_u32()?),
Type::SLONG => Signed(self.r(bo).read_i32()?),
Type::FLOAT => Float(self.r(bo).read_f32()?),
Expand Down Expand Up @@ -509,7 +507,7 @@ impl Entry {
let mut r = self.r(bo);
let mut v = Vec::new();
for _ in 0..self.count {
v.push(Signed(i32::from(r.read_i16()?)));
v.push(SignedShort(r.read_i16()?));
}
return Ok(List(v));
}
Expand Down Expand Up @@ -569,10 +567,10 @@ impl Entry {
Ok(SignedBig(i64::from(reader.read_i8()?)))
}),
Type::SHORT => self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
Ok(UnsignedBig(u64::from(reader.read_u16()?)))
Ok(Short(reader.read_u16()?))
}),
Type::SSHORT => self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
Ok(SignedBig(i64::from(reader.read_i16()?)))
Ok(SignedShort(reader.read_i16()?))
}),
Type::LONG => self.decode_offset(self.count, bo, bigtiff, limits, reader, |reader| {
Ok(Unsigned(reader.read_u32()?))
Expand Down
2 changes: 2 additions & 0 deletions src/error.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,7 @@ pub enum TiffFormatError {
UnknownPlanarConfiguration(u16),
ByteExpected(Value),
SignedByteExpected(Value),
ShortExpected(Value),
SignedShortExpected(Value),
UnsignedIntegerExpected(Value),
SignedIntegerExpected(Value),
Expand Down Expand Up @@ -122,6 +123,7 @@ impl fmt::Display for TiffFormatError {
}
ByteExpected(ref val) => write!(fmt, "Expected byte, {:?} found.", val),
SignedByteExpected(ref val) => write!(fmt, "Expected signed byte, {:?} found.", val),
ShortExpected(ref val) => write!(fmt, "Expected short, {:?} found.", val),
SignedShortExpected(ref val) => write!(fmt, "Expected signed short, {:?} found.", val),
UnsignedIntegerExpected(ref val) => {
write!(fmt, "Expected unsigned integer, {:?} found.", val)
Expand Down
32 changes: 16 additions & 16 deletions tests/encode_images.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -50,28 +50,28 @@ fn encode_decode() {
(
Tag::BitsPerSample,
ifd::Value::List(vec![
ifd::Value::UnsignedBig(8),
ifd::Value::UnsignedBig(8),
ifd::Value::UnsignedBig(8)
ifd::Value::Short(8),
ifd::Value::Short(8),
ifd::Value::Short(8)
])
),
(Tag::Compression, ifd::Value::Unsigned(1)),
(Tag::PhotometricInterpretation, ifd::Value::Unsigned(2)),
(Tag::Compression, ifd::Value::Short(1)),
(Tag::PhotometricInterpretation, ifd::Value::Short(2)),
(Tag::StripOffsets, ifd::Value::Unsigned(8)),
(Tag::SamplesPerPixel, ifd::Value::Unsigned(3)),
(Tag::SamplesPerPixel, ifd::Value::Short(3)),
(Tag::RowsPerStrip, ifd::Value::Unsigned(3334)),
(Tag::StripByteCounts, ifd::Value::Unsigned(30000)),
(Tag::XResolution, ifd::Value::Rational(1, 1)),
(Tag::YResolution, ifd::Value::Rational(1, 1)),
(Tag::ResolutionUnit, ifd::Value::Unsigned(1)),
(Tag::ResolutionUnit, ifd::Value::Short(1)),
(Tag::Artist, ifd::Value::Ascii("Image-tiff".into())),
(Tag::Predictor, ifd::Value::Unsigned(1)),
(Tag::Predictor, ifd::Value::Short(1)),
Comment on lines -58 to +68
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@weiji14 weiji14 Mar 16, 2025 •
edited
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The hard part is still this concern:

This makes sense to fix, though the annoying part is figuring out whether anywhere else in the code is relying on the current behavior. Or whether it is likely to break any downstream users and thus might warrant additional caution

Looks like some tests added in #255 around November 2024 (after this PR was opened) exposed a potential area of breakage? Old behaviour is that some of these tags (e.g. Compression, PhotometricInterpretation, SamplesPerPixel, ResolutionUnit, Predictor) were incorrectly decoded as Unsigned (u32), whereas after this PR, they will be decoded as Short (u16).

(
Tag::SampleFormat,
ifd::Value::List(vec![
ifd::Value::UnsignedBig(1),
ifd::Value::UnsignedBig(1),
ifd::Value::UnsignedBig(1)
ifd::Value::Short(1),
ifd::Value::Short(1),
ifd::Value::Short(1)
])
),
]
Expand Down Expand Up @@ -135,17 +135,17 @@ fn encode_decode_big() {
ifd::Value::Short(8)
])
),
(Tag::Compression, ifd::Value::Unsigned(1)),
(Tag::PhotometricInterpretation, ifd::Value::Unsigned(2)),
(Tag::Compression, ifd::Value::Short(1)),
(Tag::PhotometricInterpretation, ifd::Value::Short(2)),
(Tag::StripOffsets, ifd::Value::UnsignedBig(16)),
(Tag::SamplesPerPixel, ifd::Value::Unsigned(3)),
(Tag::SamplesPerPixel, ifd::Value::Short(3)),
(Tag::RowsPerStrip, ifd::Value::Unsigned(3334)),
(Tag::StripByteCounts, ifd::Value::UnsignedBig(30000)),
(Tag::XResolution, ifd::Value::Rational(1, 1)),
(Tag::YResolution, ifd::Value::Rational(1, 1)),
(Tag::ResolutionUnit, ifd::Value::Unsigned(1)),
(Tag::ResolutionUnit, ifd::Value::Short(1)),
(Tag::Artist, ifd::Value::Ascii("Image-tiff".into())),
(Tag::Predictor, ifd::Value::Unsigned(1)),
(Tag::Predictor, ifd::Value::Short(1)),
(
Tag::SampleFormat,
ifd::Value::List(vec![
Expand Down
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