图片压缩 DCT变换 实时视频 - 2

上一篇的源码进行优化，将cosx运算提取出来，变成矩阵形式。

#include "stdafx.h"
#include <string.h>
#include <iostream>
#include <math.h>

using namespace std;
#define PI 3.1415926

int _tmain(int argc, _TCHAR* argv[])
{
double dInput[] = {0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0};
int iFactor[] = {1, 1, 1, 1, 0, 0, 0, 0, 0, 0};
double dOut[10] = {0};
double dOut1[10]= {0};

const int N = sizeof(dInput)/sizeof(double);
double* pdFactor = new double[N*N];

for (int row=0; row<N; row++)
{
for (int col=0; col<N; col++)
{
if (row==0)
pdFactor[row*N+col] = cos((2*col + 1)*PI*row/(2*N)) / sqrt((double)N);
else
pdFactor[row*N+col] = cos((2*col + 1)*PI*row/(2*N)) * sqrt(2.0) / sqrt((double)N);
}
}

for (int i=0; i<N; i++)
{
for (int j=0; j<N; j++)
{
dOut[i]+= dInput[j] * pdFactor[i*N+j];
}
}
printf("\n变换前：\n");
for (int i=0; i<N; i++)
{
printf("%f\t", dInput[i]);
}

printf("\n变换后：\n");
for (int i=0; i<N; i++)
{
printf("%f\t", dOut[i]);
}

//printf("\n去除高频：\n");
//for (int i=0; i<N; i++)
//{
// dOut[i] *= iFactor[i];
// printf("%f\t", dOut[i]);
//}

printf("\n逆变换：\n");
for (int i=0; i<N; i++)
{
for (int j=0; j<N; j++)
{
dOut1[i]+= dOut[j] * pdFactor[j*N+i];
}
}

for (int i=0; i<N; i++)
{
printf("%f\t", dOut1[i]);
}

getchar();
delete[] pdFactor;
} 由此源码发现。

参数因子pdFactor,由编码的逐行积相加，变为解码的逐列的积相加。