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Fix reflected border interpolation for extreme coordinates

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This commit is contained in:
tandede
2026-08-20 11:30:09 +08:00
parent 039e02ed9c
commit 1a0e2d459d
2 changed files with 78 additions and 13 deletions
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23
modules/core/src/copy.cpp
View File

@@ -918,21 +918,18 @@ int cv::borderInterpolate( int p, int len, int borderType )
p = p < 0 ? 0 : len - 1;
else if( borderType == BORDER_REFLECT || borderType == BORDER_REFLECT_101 )
{
int delta = borderType == BORDER_REFLECT_101;
const int delta = borderType == BORDER_REFLECT_101;
if( len == 1 )
return 0;
do
{
if( p < 0 )
p = -p - 1 + delta;
else
p = len - 1 - (p - len) - delta;
}
#ifdef CV_STATIC_ANALYSIS
while(p < 0 || p >= len);
#else
while( (unsigned)p >= (unsigned)len );
#endif
const int64 period = 2LL * (len - delta);
int64 p64 = p;
p64 %= period;
if( p64 < 0 )
p64 += period;
if( p64 >= len )
p64 = period - p64 - 1 + delta;
p = (int)p64;
}
else if( borderType == BORDER_WRAP )
{

68
modules/core/test/test_misc.cpp
View File

@@ -37,6 +37,74 @@ TEST(Core_SaturateCast, NegativeNotClipped)
ASSERT_EQ(0xffffffff, val);
}
// See https://github.com/opencv/opencv/issues/29736
static int borderReflectReference(int p, int len, int borderType)
{
const int delta = borderType == BORDER_REFLECT_101;
if( len == 1 )
return 0;
while( p < 0 || p >= len )
{
if( p < 0 )
p = -p - 1 + delta;
else
p = len - 1 - (p - len) - delta;
}
return p;
}
TEST(Core_BorderInterpolate, ReflectCompatibility)
{
const int borderTypes[] = { BORDER_REFLECT, BORDER_REFLECT_101 };
const int lengths[] = { 1, 2, 3, 5, 17 };
for( size_t i = 0; i < sizeof(borderTypes) / sizeof(borderTypes[0]); i++ )
{
for( size_t j = 0; j < sizeof(lengths) / sizeof(lengths[0]); j++ )
{
for( int p = -1000; p <= 1000; p++ )
{
EXPECT_EQ(borderReflectReference(p, lengths[j], borderTypes[i]),
cv::borderInterpolate(p, lengths[j], borderTypes[i]))
<< "p=" << p << ", len=" << lengths[j]
<< ", borderType=" << borderTypes[i];
}
}
}
}
TEST(Core_BorderInterpolate, ReflectExtremeCoordinates)
{
struct TestCase
{
int p;
int len;
int borderType;
int expected;
};
const TestCase cases[] = {
{ INT_MIN, 2, BORDER_REFLECT, 0 },
{ INT_MAX, 2, BORDER_REFLECT, 0 },
{ INT_MIN, 3, BORDER_REFLECT, 1 },
{ INT_MAX, 3, BORDER_REFLECT, 1 },
{ INT_MIN, INT_MAX, BORDER_REFLECT, INT_MAX - 1 },
{ INT_MAX, INT_MAX, BORDER_REFLECT, INT_MAX - 1 },
{ INT_MIN, 2, BORDER_REFLECT_101, 0 },
{ INT_MAX, 2, BORDER_REFLECT_101, 1 },
{ INT_MIN, 3, BORDER_REFLECT_101, 0 },
{ INT_MAX, 3, BORDER_REFLECT_101, 1 },
{ INT_MIN, INT_MAX, BORDER_REFLECT_101, INT_MAX - 3 },
{ INT_MAX, INT_MAX, BORDER_REFLECT_101, INT_MAX - 2 },
};
for( size_t i = 0; i < sizeof(cases) / sizeof(cases[0]); i++ )
{
EXPECT_EQ(cases[i].expected,
cv::borderInterpolate(cases[i].p, cases[i].len, cases[i].borderType))
<< "p=" << cases[i].p << ", len=" << cases[i].len
<< ", borderType=" << cases[i].borderType;
}
}
template<typename T, typename U>
static double maxAbsDiff(const T &t, const U &u)
{