Accurate Determination of processing time when using opencv for image processing

# Include <stdio. h>
# Include <math. h>
# Include <OMP. h>
# Include <windows. h>
Large_integer m_liperffreq;
Large_integer m_liperfstart;
Large_integer liperfnow;
Double dftim;
Void getstarttime ()
{
Queryperformancefrequency (& m_liperffreq );
Queryperformancecounter (& m_liperfstart );
}

Void getendtime ()
{
Queryperformancecounter (& liperfnow );
Dftim = (liperfnow. quadpart-m_liperfstart.quadpart) * 1000.0f)/m_liperffreq.quadpart );
}

Void main ()
{
Static long num_steps= 1000000;
Double step, PI;
Double X, sum = 0.0;
Int I = 0;
Step = 1.0/(double) num_steps;
Getstarttime ();

// # Pragma OMP parallel for private (x) ction (+: Sum)
For (I = 0; I <num_steps; I ++)
{
X = (I + 0.5) * step;
Sum + = 4.0/(1.0 + x * X );
// Printf ("% F, % d \ n", omp_get_thread_num ());
}
Getendtime ();
Printf ("% F \ n", dftim );
Pi = Step * sum;
Printf ("Pi = % F \ n", Pi );

}