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#include <opencv2/opencv.hpp>

using namespace cv;
using namespace std;

// Define a pixel
typedef Point3_<uint8_t> Pixel;

void tic(double &t)
{
	t = (double)getTickCount();
}

double toc(double &t)
{
	return ((double)getTickCount() - t) / getTickFrequency();
}

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;
	}
}

int main(int argc, char** argv)
{
	Mat image = imread("butterfly.jpg");
	resize(image, image, Size(), 30, 30);
	cout << "Image size " << image.size() << endl;
	int numTrials = 10;
	double t;
	cout << "Number of trials : " << numTrials << endl;

	// Make two copies
	Mat image1 = image.clone();

	// Start timer
	tic(t);

	for (int n = 0; n < numTrials; n++)
	{
		// Naive pixel access
		for (int r = 0; r < image.rows; r++)
		{
			for (int c = 0; c < image.cols; c++)
			{
				// Obtain pixel at (r, c)
				Pixel pixel = image.at<Pixel>(r, c);
				// Apply complicatedTreshold
				complicatedThreshold(pixel);
				// Put result back
				image.at<Pixel>(r, c) = pixel;
			}

		}
	}
	cout << "Naive way: " << toc(t) << endl;

	tic(t);
	for (int n = 0; n < numTrials; n++)
	{
		// Parallel execution using C++11 lambda.
		image1.forEach<Pixel>
		(
			[](Pixel &pixel, const int* position) -> void
			{
				complicatedThreshold(pixel);
			}
		);
	}
	cout << "forEach C++11 : " << toc(t) << endl;

	return EXIT_SUCCESS;
}