Speed up and reduce memory consumption for findContours#26690
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asmorkalov merged 1 commit intoopencv:4.xfrom Dec 31, 2024
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asmorkalov
approved these changes
Dec 31, 2024
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Thank you for your work, but I tested and found that the speed of this function in version 4.11 is slower than in version 4.7. #include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;
int main()
{
Mat img = imread("111.bmp", cv::IMREAD_GRAYSCALE);
cv::Mat mask;
inRange(img, 110, 120, mask);
std::vector<std::vector<cv::Point>> v_cont;
for (int i = 0; i < 10; i++)
{
v_cont.clear();
auto start = chrono::system_clock::now();
cv::findContours(mask, v_cont, cv::RETR_EXTERNAL, cv::CHAIN_APPROX_SIMPLE);
auto end = chrono::system_clock::now();
auto duration = chrono::duration_cast<chrono::microseconds>(end - start) / 1000.;
cout << "4.11 findContours cost" << double(duration.count()) << "ms" << endl;
}
}
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Merged
Contributor
This is because this function has been rewritten from C to C++ between these releases, it needs additional refactoring of internal structures in order to return to previous speed. |
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Pull Request Readiness Checklist
Related to #26683
I ran reproducer from issue with one iteration.
Before
After
Speedup more than
2times and memory consumption reduction more than10timesSee details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
Patch to opencv_extra has the same branch name.