opencv3 Mat类的成员函数forEach

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#include<opencv2/opencv.hpp>using namespace cv;using namespace std;typedef Point3_<uint8_t> Pixel;void complicatedThreshold(Pixel &pixel){if (pow(double(pixel.x) / 10, 2.5) > 100){pixel.x = 255;pixel.y = 255;pixel.z = 255;}else{pixel.x = 0;pixel.y = 0;pixel.z = 0;}}struct Operator{void operator ()(Pixel &pixel, const int * position) const{// Perform a simple threshold operationcomplicatedThreshold(pixel);}};int main(){Mat image = imread("C:/Users/Administrator/Desktop/timg.jpg");resize(image, image, Size(1920, 1920));clock_t t1 = clock();for (int r = 0; r < image.rows; r++){for (int c = 0; c < image.cols; c++){Pixel pixel = image.at<Pixel>(r, c);complicatedThreshold(pixel);image.at<Pixel>(r, c) = pixel;}}clock_t t2 = clock();cout << t2 - t1 << "ms" << endl;/***********************************************/clock_t t3 = clock();Pixel* pixel = image.ptr<Pixel>(0, 0);const Pixel* endPixel = pixel + image.cols * image.rows;for (; pixel != endPixel; pixel++){complicatedThreshold(*pixel);}clock_t t4 = clock();cout << t4 - t3 << "ms" << endl;/***********************************************/clock_t t5 = clock();image.forEach<Pixel>(Operator());clock_t t6 = clock();cout << t6 - t5 << "ms" << endl;/***********************************************/clock_t t7 = clock();image.forEach<Pixel>([](Pixel &pixel, const int * position) -> void{complicatedThreshold(pixel);});clock_t t8 = clock();cout << t8 - t7 << "ms" << endl;/***********************************************/waitKey();return 0;}

对比之下，可以发现forEach的速度很快，因为其里面用了ParallelBody

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