Hi,
I want to understand how works is split between thread. I wrote a little program which write in each pixel thread number :
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;
class FiltreLigneParallel : public ParallelLoopBody
{
private:
bool verbose;
Mat imgSrc;
public:
FiltreLigneParallel(Mat& img) :
imgSrc(img),
verbose(false)
{}
void Verbose(bool b) { verbose = b; }
virtual void operator()(const Range& range) const
{
int tNum = getThreadNum()*16;
if (verbose)
cout << getThreadNum() << "# :Start from row " << range.start << " to " << range.end - 1 << " (" << range.end - range.start << " loops)" << endl;
for (int y = range.start; y < range.end; y++)
{
uchar *vDst = (uchar*)imgSrc.ptr(y);
for (int x = 0; x < imgSrc.cols; x++, vDst++)
*vDst= static_cast<uchar>(tNum);
}
}
FiltreLigneParallel& operator=(const FiltreLigneParallel &) {
return *this;
};
};
class FiltreLigne {
uchar *pData;
public:
FiltreLigne(uchar *p) { pData=p;};
void operator ()(uchar &pixel, const int * position) const {
int tNum = getThreadNum()*16;
pixel = static_cast<uchar>(tNum);;
}
};
void main(void)
{
Mat img(512,512,CV_8UC1,Scalar(255));
img.forEach<uchar>(FiltreLigne(img.ptr(0)));
imwrite("forEach.png",img);
Mat img2(512, 512, CV_8UC1, Scalar(255));
FiltreLigneParallel x(img2);
parallel_for_(Range(0, img2.rows), x, getNumThreads());
imwrite("parallel_for.png", img2);
waitKey();
}
Results are :
forEach
and parallel_for
Why foreach.png is not regular like parallel_for_?
Configuration windows 10, VS 2015, and concurrency for thread