OpenCV使用不同方式訪問圖像數據

OpenCV對圖像數據的訪問方式如下代碼所示（opencv2.0以上）：

/************************************************************************/
/*                           OpenCV使用不同方式訪問圖像數據                                   */
/************************************************************************/
	
#include <opencv2/opencv.hpp>
#include <opencv2/highgui/highgui.hpp>
using namespace cv;
#include <iostream>
using namespace std;

int main(int argc, char ** argv)
{
	//方法1：使用cvGet2D()函數訪問
	double t = (double)getTickCount();
	Mat imgx(1000, 1000, CV_32F);
	IplImage imgIP = imgx;
	for (int i=0; i<1000; i++)
	{
		for (int j=0; j<1000; j++)
		{
			cvGet2D(&imgIP,i,j);
		}
	}
	t = (double)getTickCount() - t;
	printf("方法1 - Time: %gms\n", t*1000/getTickFrequency());

	//方法2：使用at操作符訪問
	t = (double)getTickCount();
	Mat img1(1000, 1000, CV_32F);
	for (int i=0; i<1000; i++)
	{
		for (int j=0; j<1000; j++)
		{
			img1.at<float>(i,j) = 3.2f;
		}
	}
	t = (double)getTickCount() - t;
	printf("方法2 - Time: %gms\n", t*1000/getTickFrequency());

	//方法3：使用ptr指針訪問
	t = (double)getTickCount();
	Mat img2(1000, 1000, CV_32F);
	for (int i=0; i<1000; i++)
	{
		for (int j=0; j<1000; j++)
		{
			img2.ptr<float>(i)[j] = 3.2f;
		}
	}
	t = (double)getTickCount() - t;
	printf("方法3  - Time: %gms\n", t*1000/getTickFrequency());

	//方法4：使用data數組訪問
	t = (double)getTickCount();
	Mat img4(1000, 1000, CV_32F);
	for (int i=0; i<1000; i++)
	{
		for (int j=0; j<1000; j++)
		{
			((float*)img4.data)[i*1000+j] = 3.2f;
		}
	}
	t = (double)getTickCount() - t;
	printf("方法4  - Time: %gms\n", t*1000/getTickFrequency()); 

	//方法5：使用指針訪問
	t = (double)getTickCount();
	Mat img3(1000, 1000, CV_32F);
	float* pData = (float*)img3.data;
	for (int i=0; i<1000; i++)
	{
		for (int j=0; j<1000; j++)
		{
			*(pData) = 3.2f;
			pData++;
		}
	}
	t = (double)getTickCount() - t;
	printf("方法5  - Time: %gms\n", t*1000/getTickFrequency());
	//system("pause");
}

運行結果如圖：