分析rgb和yuv文件的三个通道的概率分布，并计算各自的熵

分析rgb和yuv文件的三个通道的概率分布，并计算各自的熵

rgb文件

#include<iostream>
#include<math.h>
using namespace std;

#define RES 256*256

int main()
{
    unsigned char r[RES] = {0},g[RES] = {0},b[RES] = {0};
    double Hr = 0, Hg = 0, Hb = 0;

    FILE *RGB_BUFFER;
    fopen_s(&RGB_BUFFER, "down.rgb", "rb");
    
	unsigned char a[RES * 3] = {0};
    fread(a, 1, RES * 3, RGB_BUFFER);
    
	for (int i = 0,j = 0 ; j < RES*3 ; i++, j += 3)
    {
        b[i] = a[j];
        g[i] = a[j + 1];
        r[i] = a[j + 2];
    }
	
	double r1[256] = {0},g1[256] = {0},b1[256] = {0};
    
	for (int i = 0; i < RES; i++)
    {
        r1[r[i]]++; 
        g1[g[i]]++;
        b1[b[i]]++;
    }
    for (int i = 0; i < 256; i++)
    {
        r1[i] = r1[i] / (RES);
        g1[i] = g1[i] / (RES);
        b1[i] = b1[i] / (RES);
    }
    for (int i = 0; i < 256; i++)
    {
		if (r1[i] != 0) 
		{ 
			Hr += -r1[i] * log(r1[i])/log(2*1.0);
		}
        if (g1[i] != 0) 
		{ 
			Hg += -g1[i] * log(g1[i])/log(2*1.0);
		}
        if (b1[i] != 0) 
		{
			Hb += -b1[i] * log(b1[i])/log(2*1.0);
		}
    }
    printf("H(r)=%f\nH(g)=%f\nH(b)=%f\n",Hr,Hg,Hb);
   
	getchar();
    
    return 0;
}

执行结果

YUV文件

#include<iostream>
#include<math.h>
using namespace std;

#define RES 256*256

int main()
{
    unsigned char y[RES] = {0},u[RES/4] = {0},v[RES/4] = {0};
    double Hy = 0, Hu = 0, Hv = 0;

    FILE *YUV_BUFFER;
    fopen_s(&YUV_BUFFER, "down.yuv", "rb");

	unsigned char a[98304];     //RES*1.5 = 98304
    fread(a, 1, RES * 1.5, YUV_BUFFER);
    
	for (int i = 0 ; i < RES ; i++)
    {
		y[i] = a[i];
    }
	for (int i = RES ; i < RES*1.25 ; i++)
	{
		u[i - RES] = a[i];
		v[i - RES] = a[i + 16384];    //RES*0.25 = 16384
	}

	double y1[256] = {0},u1[256] = {0},v1[256] = {0};
    
	for (int i = 0; i < RES; i++)
    {
        y1[y[i]]++; 
    }

	for (int i = 0; i < RES/4; i++)
    {
        u1[u[i]]++;
        v1[v[i]]++;
    }
    
	for (int i = 0; i < 256; i++)
    {
        y1[i] = y1[i] / (RES);
        u1[i] = u1[i] / (RES/4);
        v1[i] = v1[i] / (RES/4);
    }
    for (int i = 0; i < 256; i++)
    {
		if (y1[i] != 0) 
		{ 
			Hy += -y1[i] * log(y1[i])/log(2*1.0); 
		}
        if (u1[i] != 0) 
		{ 
			Hu += -u1[i] * log(u1[i])/log(2*1.0); 
		}
        if (v1[i] != 0) 
		{ 
			Hv += -v1[i] * log(v1[i])/log(2*1.0); 
		}
    }
    printf("H(y)=%f\nH(u)=%f\nH(v)=%f\n",Hy,Hu,Hv);
   
	getchar();
    
    return 0;
}

执行结果

总结

YUV三轨道熵值都比RGB三轨道熵值低，压缩程度较高。