//2018.1.19_21:09 by Cooper Liu
//Questions? Contact me: [email protected]
//本程序为C++工程，编译环境需要配置openCV
#include <iostream>  
#include <opencv2/core/core.hpp>  
#include <opencv2/highgui/highgui.hpp>  
//#include<opencv2/opencv.hpp>//如果要包含所有库

using namespace cv;
//将mat类型转换为二维数组的类型
double** transform(Mat &img, int row, int col)
{
	int i = 0, j = 0;


	double **ptr = (double **)malloc(row*sizeof(double *));//二维数组ptr[][]
	for (i = 0; i < row; i++)
		ptr[i] = (double *)malloc(col*sizeof(double));

	//新图的大小以及指向它的指针
	Mat img2 = Mat(row, col, CV_8UC1);//图像img2：row*col大小
	double *ptmp = NULL;//这是关键的指针！！

	for (i = 0; i < row; i++)
	{
		ptmp = img2.ptr<double>(i);//指针指向img2的第i行
		for (j = 0; j < col; j++)
		{
			ptr[i][j] = img.at<double>(i, j);//img的矩阵数据传给二维数组ptr[][]
			ptmp[j] = ptr[i][j];//二维数组数据传给img2的第i行第j列
		}
	}   
	waitKey(100000);
	return ptr;
}
double** mydct（double **ptr2, int M, int N）
{
	int p, q, m, n;
	double ap, aq;
	double output[M][N];
	for (p = 0; p < M - 1; p++)
	{
		for (q = 0; q < N - 1; q++)
		{

			if（p == 0）
			{
				ap = sqrt(1.0 / M);

			}
			else
			{
				ap = sqrt(2.0 / M);
			}
			if（q == 0）
			{
				aq = sqrt(1.0 / N);
			}
			else
			{
				aq = sqrt(2.0 / N);
			}
			double tmp = 0.0;
			for (m = 0; m < M - 1; m++)
			{
				for (n = 0; n < N - 1; n++)
				{
					tmp += ptr2[m][n] * cos((2 * m + 1)*p*PI / (2.0 * M)) * cos((2 * n + 1)*q*PI / (2.0 * N));

				}
			}
			output[p][q] = ap*aq*temp;
		}

	}

}
//将二维数组转化成mat类型以图片形式输出
double** arraytomat（double **result, int M, int N）
{
	int i, j;
	//定义mat类型存放新图片
	Mat img2 = Mat(M, N, CV_8UC1);//图像img2：row*col大小
	double *ptmp = NULL;//这是关键的指针！！
	for (i = 0; i < M; i++)
	{
		ptmp = img2.ptr<double>(i);//指针指向img2的第i行
		for (j = 0; j < N; j++)
		{
			//output[i][j] = img.at<double>(i, j);//img的矩阵数据传给二维数组ptr[][]  此步骤已经在transform中存入了二维数组
			ptmp[j] = result[i][j];//二维数组数据传给img2的第i行第j列
		}

	}
	Mat fimage2;
	img2.convertTo(fimage2, CV_8UC1);//将矩阵转化为无符号
	namedWindow("dct后图片");//显示
	imshow("dct后图片", fimage2);
}
void main()
{
	//这一段程序实现：图像img -> ptr[][] -> 图像img2 的传递过程，即图像->二维数组->图像

	Mat img = imread("pic.png", CV_LOAD_IMAGE_GRAYSCALE);//读取图像img。0表示转换为灰度图像读入
	namedWindow("原图");
	imshow("原图", img);
	//将图片img转化成浮点数矩阵fimage，然后进行dct的变换----------
	Mat fimage;
	img.convertTo(fimage, CV_64FC1);
	int row =fimage.rows;
	int col =fimage.cols;
	double **ptr2 = transform(fimage, fimage.rows, fimage.cols);
	//对转换成的矩阵作dct变换
	double **result = mydct（ptr2, row, col）;
	arraytomat(result, row, col);
}