DCT / IDCT

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/* DCT与IDCT变换的简单实现，不是最优解 */

#include <iostream>
#include <math.h>

using namespace std;

#define NUM 8
#define PI 3.1415926

short round(double a)
{
if (a >= 0)
{
return (short)(a + 0.5);
}
else
{
return (short)(a - 0.5);
}
}

// DCT - Discrete Cosine Transform

void DCT(short data[NUM][NUM])
{
short output[NUM][NUM];
double ALPHA, BETA;
short u = 0;
short v = 0;
short i = 0;
short j = 0;

for(u = 0; u < NUM; u++)
{
for(v = 0; v < NUM; v++)
{
if(u == 0)
{
ALPHA = sqrt(1.0 / NUM);
}
else
{
ALPHA = sqrt(2.0 / NUM);
}

if(v == 0)
{
BETA = sqrt(1.0 / NUM);
}
else
{
BETA = sqrt(2.0 / NUM);
}

double tmp = 0.0;

for(i = 0; i < NUM; i++)
{
for(j = 0; j < NUM; j++)
{
tmp += data[i][j] * cos((2*i+1)*u*PI/(2.0 * NUM)) * cos((2*j+1)*v*PI/(2.0 * NUM));
}
}
output[u][v] = round(ALPHA * BETA * tmp);
}
}
memset(data, 0, NUM * NUM * sizeof(short));
memcpy(data, output, NUM * NUM * sizeof(short));

}

// Inverse DCT (IDCT)

void IDCT(short data[NUM][NUM])
{
short output[NUM][NUM];
double ALPHA, BETA;
short u = 0;
short v = 0;
short i = 0;
short j = 0;

for(i = 0; i < NUM; i++)
{
for(short j = 0; j < NUM; j++)
{
double tmp = 0.0;

for(short u = 0; u < NUM; u++)
{
for(v = 0; v < NUM; v++)
{
if(u == 0)
{
ALPHA = sqrt(1.0 / NUM);
}
else
{
ALPHA = sqrt(2.0 / NUM);
}
if(v == 0)
{
BETA = sqrt(1.0 / NUM);
}
else
{
BETA = sqrt(2.0 / NUM);
}
tmp += ALPHA * BETA * data[u][v] * cos((2*i+1)*u*PI/(2.0 * NUM)) * cos((2*j+1)*v*PI/(2.0 * NUM));
}
}
output[i][j] = round(tmp);
}
}
memset(data, 0, NUM * NUM * sizeof(short));
memcpy(data, output, NUM * NUM * sizeof(short));
}

int main(void)
{
short i = 0;
short j = 0;
short u = 0;
short v = 0;

// 8 x 8 的图像数据

short input[NUM][NUM] =
{
{ 89, 101, 114, 125, 126, 115, 105, 96 },

{ 97, 115, 131, 147, 149, 135, 123, 113 },

{ 114, 134, 159, 178, 175, 164, 149, 137 },

{ 121, 143, 177, 196, 201, 189, 165, 150 },

{ 119, 141, 175, 201, 207, 186, 162, 144 },

{ 107, 130, 165, 189, 192, 171, 144, 125 },

{ 97, 119, 149, 171, 172, 145, 117, 96 },

{ 88, 107, 136, 156, 155, 129, 97, 75 }

};

DCT(input); // DCT

cout << "\nThe result of DCT:\n" << endl;

for(u = 0; u < NUM; u++)
{
for(v = 0; v < NUM; v++)
{
cout << input[u][v] << '/t';
}
cout << endl;
}

IDCT(input); // IDCT

cout << "\nThe result of IDCT:\n" << endl;

for(i = 0; i < NUM; i++)
{
for(short j = 0; j < NUM; j++)
{
cout << input[i][j] << '/t';
}
cout << endl;
}
system("pause");
return 0;
}

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