how to change openmp to tbb? - openmp

Question

hellow,
I want change my code openmp to TBB
this is my code.
for (long y = 0; y < _src.rows; y++)
{
#pragma omp parallel
{
#pragma omp for firstprivate(i)
for (long x = 0; x < _src.cols; x++)
{
const uchar* data = _src.ptr((int)y, (int)x);
i = (y * _src.cols + x);
//update model+ background subtract
// cout << "parallel: " << i << endl;
uchar include = 0;
int result = _cvCheckPixelBackgroundNP(i, data, nchannels,
m_nN, m_aModel, m_fTb, m_nkNN, m_fTau, m_bShadowDetection, include);
_cvUpdatePixelBackgroundNP(i, data, nchannels,
m_nN, m_aModel,
m_nNextLongUpdate,
m_nNextMidUpdate,
m_nNextShortUpdate,
m_aModelIndexLong,
m_aModelIndexMid,
m_aModelIndexShort,
m_nLongCounter,
m_nMidCounter,
m_nShortCounter,
m_nLongUpdate,
m_nMidUpdate,
m_nShortUpdate,
include
);
switch (result)
{
case 0:
//foreground
*_dst.ptr((int)y, (int)x) = 255;
break;
case 1:
//background
*_dst.ptr((int)y, (int)x) = 0;
break;
case 2:
//shadow
*_dst.ptr((int)y, (int)x) = nShadowDetection;
break;
}
// i++;
}
}
}
};
I try to change TBB code
long i = 0;
tbb::parallel_for(tbb::blocked_range2d<int>(0,_src.rows,0,_src.cols)
, [&](tbb::blocked_range2d<int>r) {
for (int y = r.rows().begin(); y < r.rows().end();y++)
{
for (int x = r.cols().begin(); x != r.cols().end(); x++)
{
const uchar* data = _src.ptr((int)y, (int)x);
i = (y * _src.cols + x);
//update model+ background subtract
uchar include = 0;
int result = _cvCheckPixelBackgroundNP(i, data, nchannels,
m_nN, m_aModel, m_fTb, m_nkNN, m_fTau, m_bShadowDetection, include);
_cvUpdatePixelBackgroundNP(i, data, nchannels,
m_nN, m_aModel,
m_nNextLongUpdate,
m_nNextMidUpdate,
m_nNextShortUpdate,
m_aModelIndexLong,
m_aModelIndexMid,
m_aModelIndexShort,
m_nLongCounter,
m_nMidCounter,
m_nShortCounter,
m_nLongUpdate,
m_nMidUpdate,
m_nShortUpdate,
include
);
switch (result)
{
case 0:
//foreground
*_dst.ptr((int)y, (int)x) = 255;
break;
case 1:
//background
*_dst.ptr((int)y, (int)x) = 0;
break;
case 2:
//shadow
*_dst.ptr((int)y, (int)x) = nShadowDetection;
break;
}
// i++;
}
}
},tbb::auto_partitioner());
and I did change time. two result time is simillary but,
performance is different.
how can i fix it? sorry for my bad english.