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Merge pull request #29640 from yvonnelxxxx/fix/int-overflow-absdiff

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fix: signed-integer-overflow in c_absdiff<int>
This commit is contained in:
Abhishek Gola
2026-08-06 19:29:06 +05:30
committed by GitHub
parent 59a0461d50 5a5ac33c87
commit 77dfa297d0
3 changed files with 37 additions and 1 deletions
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2
modules/core/include/opencv2/core.hpp
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@@ -1437,7 +1437,7 @@ The function cv::absdiff calculates:
\f[\texttt{dst}(I) = \texttt{saturate} (| \texttt{src1} - \texttt{src2}(I) |)\f]
where I is a multi-dimensional index of array elements. In case of
multi-channel arrays, each channel is processed independently.
@note Saturation is not applied when the arrays have the depth CV_32S.
@note Saturation might not be applied when the arrays have the depth CV_32S.
You may even get a negative value in the case of overflow.
@note (Python) Be careful to difference behaviour between src1/src2 are single number and they are tuple/array.
`absdiff(src,X)` means `absdiff(src,(X,X,X,X))`.

3
modules/core/src/arithm.simd.hpp
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@@ -168,6 +168,9 @@ inline schar c_absdiff(schar a, schar b)
template<>
inline short c_absdiff(short a, short b)
{ return saturate_cast<short>(std::abs(a - b)); }
template<> inline int c_absdiff<int>(int a, int b){
return (int)((unsigned)std::max(a, b) - (unsigned)std::min(a, b));
}
// specializations to prevent "-0" results
template<>
inline float c_absdiff<float>(float a, float b)

33
modules/core/test/test_arithm.cpp
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@@ -2848,6 +2848,39 @@ TEST(Core_ConvertTo, regression_12121)
}
}
TEST(Core_AbsDiff, regression_29639_integer_overflow)
{
const struct { int a, b; } cases[] = {
{ INT_MIN, 0 },
{ 0, INT_MIN },
{ INT_MIN, INT_MAX },
{ INT_MAX, INT_MIN },
{ INT_MIN, -1 },
{ INT_MAX, 0 },
{ 7, -5 },
};
for (const auto& c : cases)
{
cv::Mat a(3, 11, CV_32SC1, cv::Scalar(c.a));
cv::Mat b(3, 11, CV_32SC1, cv::Scalar(c.b));
cv::Mat d;
cv::absdiff(a, b, d);
int wraparound = (int)((unsigned)std::max(c.a, c.b) - (unsigned)std::min(c.a, c.b));
int64 diff = (int64)c.a - (int64)c.b;
int saturated = cv::saturate_cast<int>(diff < 0 ? -diff : diff);
int first = d.at<int>(0, 0);
int last = d.at<int>(d.rows - 1, d.cols - 1);
EXPECT_TRUE(first == wraparound || first == saturated)
<< "absdiff(" << c.a << ", " << c.b << ") first element (vector path) = "
<< first << ", expected wraparound " << wraparound << " or saturate " << saturated;
EXPECT_TRUE(last == wraparound || last == saturated)
<< "absdiff(" << c.a << ", " << c.b << ") last element (scalar remainder) = "
<< last << ", expected wraparound " << wraparound << " or saturate " << saturated;
}
}
TEST(Core_MeanStdDev, regression_multichannel)
{
{