111.txt

该函数用于对图像进行傅立叶变换 采用蝶形算法进行快速付立叶变换该函数用于对图像进行傅立叶变换 采用蝶形算法进行快速付立叶变换

void CMyDoc::FFT(double *TD1, double *TD2, double *FD1, double *FD2, int r)
{
    //该函数用于对图像进行傅立叶变换

	// 付立叶变换点数
	LONG count=1<<r;
	// 循环变量
	int		i,j,k;
	// 中间变量
	int		bfsize,p;
	// 角度
	double	angle;
	
	double *W1,*W2,*X11,*X12,*X21,*X22,*X1,*X2;
	
	// 分配运算所需存储器
	W1  = new double[count / 2];
    W2  = new double[count / 2];
	X11 = new double[count];
	X12 = new double[count];
	X21 = new double[count];
	X22 = new double[count];
	
	// 计算加权系数
	for(i = 0; i < count / 2; i++)
	{
		angle = -i * 3.1415926535 * 2 / count;
		W1[i]=double(cos(angle));
		W2[i]=double(sin(angle));
	}
	
	// 将时域点写入X1
	memcpy(X11, TD1, sizeof(double) * count);
	memcpy(X12, TD2, sizeof(double) * count);
	
	// 采用蝶形算法进行快速付立叶变换
	for(k = 0; k < r; k++)
	{
		for(j = 0; j < 1 << k; j++)
		{
			bfsize = 1 << (r-k);
			for(i = 0; i < bfsize / 2; i++)
			{
				p = j * bfsize;
				X21[i + p] = X11[i + p] + X11[i + p + bfsize / 2];
                X22[i + p] = X12[i + p] + X12[i + p + bfsize / 2];
				X21[i + p + bfsize / 2] = (X11[i + p] - X11[i + p + bfsize / 2]) * W1[i * (1<<k)]
					                      -(X12[i + p] - X12[i + p + bfsize / 2]) * W2[i * (1<<k)];
                X22[i + p + bfsize / 2] = (X11[i + p] - X11[i + p + bfsize / 2]) * W2[i * (1<<k)]
					                      +(X12[i + p] - X12[i + p + bfsize / 2]) * W1[i * (1<<k)];

			}
		}
		X1  = X11;
		X2  = X12;
		X11 = X21;
		X12 = X22;
		X21 = X1;
		X22 = X2;
	}
	
	// 重新排序
	for(j = 0; j < count; j++)
	{
		p = 0;
		for(i = 0; i < r; i++)
		{
			if (j&(1<<i))
			{
				p+=1<<(r-i-1);
			}
		}
		FD1[j]=X11[p];
		FD2[j]=X12[p];
	}
	
	// 释放内存
	delete W1;
	delete W2;
	delete X11;
	delete X12;
	delete X21;
	delete X22;
}
//17.对图像进行傅立叶变换函数代码完毕