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Merged
merged 1 commit into from
Apr 7, 2020
Merged

Enable Otsu thresholding for CV_16UC1 images #16640

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77 changes: 53 additions & 24 deletions modules/imgproc/src/thresh.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1125,31 +1125,24 @@ static bool ipp_getThreshVal_Otsu_8u( const unsigned char* _src, int step, Size
}
#endif

static double
getThreshVal_Otsu_8u( const Mat& _src )
template<typename T, size_t BinsOnStack = 0u>
static double getThreshVal_Otsu( const Mat& _src, const Size& size)
{
Size size = _src.size();
int step = (int) _src.step;
if( _src.isContinuous() )
{
size.width *= size.height;
size.height = 1;
step = size.width;
}

#ifdef HAVE_IPP
unsigned char thresh = 0;
CV_IPP_RUN_FAST(ipp_getThreshVal_Otsu_8u(_src.ptr(), step, size, thresh), thresh);
#endif

const int N = 256;
int i, j, h[N] = {0};
const int N = std::numeric_limits<T>::max() + 1;
int i, j;
#if CV_ENABLE_UNROLLED
int h_unrolled[3][N] = {};
AutoBuffer<int, 4 * BinsOnStack> hBuf(4 * N);
#else
AutoBuffer<int, BinsOnStack> hBuf(N);
#endif
memset(hBuf.data(), 0, hBuf.size() * sizeof(int));
int* h = hBuf.data();
#if CV_ENABLE_UNROLLED
int* h_unrolled[3] = {h + N, h + 2 * N, h + 3 * N };
#endif
for( i = 0; i < size.height; i++ )
{
const uchar* src = _src.ptr() + step*i;
const T* src = _src.ptr<T>(i, 0);
j = 0;
#if CV_ENABLE_UNROLLED
for( ; j <= size.width - 4; j += 4 )
Expand Down Expand Up @@ -1177,7 +1170,7 @@ getThreshVal_Otsu_8u( const Mat& _src )
double mu1 = 0, q1 = 0;
double max_sigma = 0, max_val = 0;

for( i = 0; i < N; i++ )
for(i = 0; i < N; i++ )
{
double p_i, q2, mu2, sigma;

Expand All @@ -1198,10 +1191,44 @@ getThreshVal_Otsu_8u( const Mat& _src )
max_val = i;
}
}

return max_val;
}

static double
getThreshVal_Otsu_8u( const Mat& _src )
{
Size size = _src.size();
int step = (int) _src.step;
if( _src.isContinuous() )
{
size.width *= size.height;
size.height = 1;
step = size.width;
}

#ifdef HAVE_IPP
unsigned char thresh = 0;
CV_IPP_RUN_FAST(ipp_getThreshVal_Otsu_8u(_src.ptr(), step, size, thresh), thresh);
#else
CV_UNUSED(step);
#endif

return getThreshVal_Otsu<uchar, 256u>(_src, size);
}

static double
getThreshVal_Otsu_16u( const Mat& _src )
{
Size size = _src.size();
if( _src.isContinuous() )
{
size.width *= size.height;
size.height = 1;
}

return getThreshVal_Otsu<ushort>(_src, size);
}

static double
getThreshVal_Triangle_8u( const Mat& _src )
{
Expand Down Expand Up @@ -1526,8 +1553,10 @@ double cv::threshold( InputArray _src, OutputArray _dst, double thresh, double m
CV_Assert( automatic_thresh != (CV_THRESH_OTSU | CV_THRESH_TRIANGLE) );
if( automatic_thresh == CV_THRESH_OTSU )
{
CV_Assert( src.type() == CV_8UC1 );
thresh = getThreshVal_Otsu_8u( src );
int src_type = src.type();
CV_CheckType(src_type, src_type == CV_8UC1 || src_type == CV_16UC1, "THRESH_OTSU mode");
thresh = src.type() == CV_8UC1 ? getThreshVal_Otsu_8u( src )
: getThreshVal_Otsu_16u( src );
}
else if( automatic_thresh == CV_THRESH_TRIANGLE )
{
Expand Down
80 changes: 74 additions & 6 deletions modules/imgproc/test/test_thresh.cpp
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -46,7 +46,7 @@ namespace opencv_test { namespace {
class CV_ThreshTest : public cvtest::ArrayTest
{
public:
CV_ThreshTest();
CV_ThreshTest(int test_type = 0);

protected:
void get_test_array_types_and_sizes( int test_case_idx, vector<vector<Size> >& sizes, vector<vector<int> >& types );
Expand All @@ -57,16 +57,22 @@ class CV_ThreshTest : public cvtest::ArrayTest
int thresh_type;
double thresh_val;
double max_val;
int extra_type;
};


CV_ThreshTest::CV_ThreshTest()
CV_ThreshTest::CV_ThreshTest(int test_type)
{
CV_Assert( (test_type & CV_THRESH_MASK) == 0 );
test_array[INPUT].push_back(NULL);
test_array[OUTPUT].push_back(NULL);
test_array[REF_OUTPUT].push_back(NULL);
optional_mask = false;
element_wise_relative_error = true;
extra_type = test_type;
// Reduce number of test with automated thresholding
if (extra_type != 0)
test_case_count = 250;
}


Expand All @@ -78,6 +84,12 @@ void CV_ThreshTest::get_test_array_types_and_sizes( int test_case_idx,
cvtest::ArrayTest::get_test_array_types_and_sizes( test_case_idx, sizes, types );
depth = depth == 0 ? CV_8U : depth == 1 ? CV_16S : depth == 2 ? CV_16U : depth == 3 ? CV_32F : CV_64F;

if ( extra_type == CV_THRESH_OTSU )
{
depth = cvtest::randInt(rng) % 2 == 0 ? CV_8U : CV_16U;
cn = 1;
}

types[INPUT][0] = types[OUTPUT][0] = types[REF_OUTPUT][0] = CV_MAKETYPE(depth,cn);
thresh_type = cvtest::randInt(rng) % 5;

Expand Down Expand Up @@ -123,18 +135,73 @@ double CV_ThreshTest::get_success_error_level( int /*test_case_idx*/, int /*i*/,
void CV_ThreshTest::run_func()
{
cvThreshold( test_array[INPUT][0], test_array[OUTPUT][0],
thresh_val, max_val, thresh_type );
thresh_val, max_val, thresh_type | extra_type);
}


static double compute_otsu_thresh(const Mat& _src)
{
int depth = _src.depth();
int width = _src.cols, height = _src.rows;
const int N = 65536;
std::vector<int> h(N, 0);
int i, j;
double mu = 0, scale = 1./(width*height);
for(i = 0; i < height; ++i)
{
for(j = 0; j < width; ++j)
{
const int val = depth == CV_16UC1 ? (int)_src.at<ushort>(i, j) : (int)_src.at<uchar>(i,j);
h[val]++;
}
}
for( i = 0; i < N; i++ )
{
mu += i*(double)h[i];
}

mu *= scale;
double mu1 = 0, q1 = 0;
double max_sigma = 0, max_val = 0;

for( i = 0; i < N; i++ )
{
double p_i, q2, mu2, sigma;

p_i = h[i]*scale;
mu1 *= q1;
q1 += p_i;
q2 = 1. - q1;

if( std::min(q1,q2) < FLT_EPSILON || std::max(q1,q2) > 1. - FLT_EPSILON )
continue;

mu1 = (mu1 + i*p_i)/q1;
mu2 = (mu - q1*mu1)/q2;
sigma = q1*q2*(mu1 - mu2)*(mu1 - mu2);
if( sigma > max_sigma )
{
max_sigma = sigma;
max_val = i;
}
}

return max_val;
}

static void test_threshold( const Mat& _src, Mat& _dst,
double thresh, double maxval, int thresh_type )
double thresh, double maxval, int thresh_type, int extra_type )
{
int i, j;
int depth = _src.depth(), cn = _src.channels();
int width_n = _src.cols*cn, height = _src.rows;
int ithresh = cvFloor(thresh);
int imaxval, ithresh2;
if (extra_type == CV_THRESH_OTSU)
{
thresh = compute_otsu_thresh(_src);
ithresh = cvFloor(thresh);
}

if( depth == CV_8U )
{
Expand All @@ -157,7 +224,7 @@ static void test_threshold( const Mat& _src, Mat& _dst,
imaxval = cvRound(maxval);
}

assert( depth == CV_8U || depth == CV_16S || depth == CV_16U || depth == CV_32F || depth == CV_64F );
CV_Assert( depth == CV_8U || depth == CV_16S || depth == CV_16U || depth == CV_32F || depth == CV_64F );

switch( thresh_type )
{
Expand Down Expand Up @@ -415,10 +482,11 @@ static void test_threshold( const Mat& _src, Mat& _dst,
void CV_ThreshTest::prepare_to_validation( int /*test_case_idx*/ )
{
test_threshold( test_mat[INPUT][0], test_mat[REF_OUTPUT][0],
thresh_val, max_val, thresh_type );
thresh_val, max_val, thresh_type, extra_type );
}

TEST(Imgproc_Threshold, accuracy) { CV_ThreshTest test; test.safe_run(); }
TEST(Imgproc_Threshold, accuracyOtsu) { CV_ThreshTest test(CV_THRESH_OTSU); test.safe_run(); }

BIGDATA_TEST(Imgproc_Threshold, huge)
{
Expand Down