两个经典的RGB与YUV转换函数

 

#include "convert.h"

// Conversion from RGB to YUV420

int RGB2YUV_YR[256], RGB2YUV_YG[256], RGB2YUV_YB[256];

int RGB2YUV_UR[256], RGB2YUV_UG[256], RGB2YUV_UBVR[256];

int RGB2YUV_VG[256], RGB2YUV_VB[256];

// Conversion from YUV420 to RGB24

static long int crv_tab[256];

static long int cbu_tab[256];

static long int cgu_tab[256];

static long int cgv_tab[256];

static long int tab_76309[256];

static unsigned char clp[1024]; //for clip in CCIR601

//

// Table used for RGB to YUV420 conversion

//

void InitLookupTable()

{

int i;

for (i = 0; i < 256; i++) RGB2YUV_YR[i] = (float)65.481 * (i<<8);

for (i = 0; i < 256; i++) RGB2YUV_YG[i] = (float)128.553 * (i<<8);

for (i = 0; i < 256; i++) RGB2YUV_YB[i] = (float)24.966 * (i<<8);

for (i = 0; i < 256; i++) RGB2YUV_UR[i] = (float)37.797 * (i<<8);

for (i = 0; i < 256; i++) RGB2YUV_UG[i] = (float)74.203 * (i<<8);

for (i = 0; i < 256; i++) RGB2YUV_VG[i] = (float)93.786 * (i<<8);

for (i = 0; i < 256; i++) RGB2YUV_VB[i] = (float)18.214 * (i<<8);

for (i = 0; i < 256; i++) RGB2YUV_UBVR[i] = (float)112 * (i<<8);

}

//

// Convert from RGB24 to YUV420

//

int ConvertRGB2YUV(int w,int h,unsigned char *bmp,unsigned int *yuv)

{

unsigned int *u,*v,*y,*uu,*vv;

unsigned int *pu1,*pu2,*pu3,*pu4;

unsigned int *pv1,*pv2,*pv3,*pv4;

unsigned char *r,*g,*b;

int i,j;

uu=new unsigned int[w*h];

vv=new unsigned int[w*h];

if(uu==NULL || vv==NULL)

return 0;

y=yuv;

u=uu;

v=vv;

// Get r,g,b pointers from bmp image data....

r=bmp;

g=bmp+1;

b=bmp+2;

//Get YUV values for rgb values...

for(i=0;i<h;i++)

{

for(j=0;j<w;j++)

{

*y++=( RGB2YUV_YR[*r] +RGB2YUV_YG[*g]+RGB2YUV_YB[*b]+1048576)>>16;

*u++=(-RGB2YUV_UR[*r] -RGB2YUV_UG[*g]+RGB2YUV_UBVR[*b]+8388608)>>16;

*v++=( RGB2YUV_UBVR[*r]-RGB2YUV_VG[*g]-RGB2YUV_VB[*b]+8388608)>>16;

r+=3;

g+=3;

b+=3;

}

}

// Now sample the U & V to obtain YUV 4:2:0 format

// Sampling mechanism...

/* @ -> Y

# -> U or V

@ @ @ @

# #

@ @ @ @

@ @ @ @

# #

@ @ @ @

*/

// Get the right pointers...

u=yuv+w*h;

v=u+(w*h)/4;

// For U

pu1=uu;

pu2=pu1+1;

pu3=pu1+w;

pu4=pu3+1;

// For V

pv1=vv;

pv2=pv1+1;

pv3=pv1+w;

pv4=pv3+1;

// Do sampling....

for(i=0;i<h;i+=2)

{

for(j=0;j<w;j+=2)

{

*u++=(*pu1+*pu2+*pu3+*pu4)>>2;

*v++=(*pv1+*pv2+*pv3+*pv4)>>2;

pu1+=2;

pu2+=2;

pu3+=2;

pu4+=2;

pv1+=2;

pv2+=2;

pv3+=2;

pv4+=2;

}

pu1+=w;

pu2+=w;

pu3+=w;

pu4+=w;

pv1+=w;

pv2+=w;

pv3+=w;

pv4+=w;

}

delete uu;

delete vv;

return 1;

}

//

//Initialize conversion table for YUV420 to RGB

//

void InitConvertTable()

{

long int crv,cbu,cgu,cgv;

int i,ind;

crv = 104597; cbu = 132201; /* fra matrise i global.h */

cgu = 25675; cgv = 53279;

for (i = 0; i < 256; i++) {

crv_tab[i] = (i-128) * crv;

cbu_tab[i] = (i-128) * cbu;

cgu_tab[i] = (i-128) * cgu;

cgv_tab[i] = (i-128) * cgv;

tab_76309[i] = 76309*(i-16);

}

for (i=0; i<384; i++)

clp[i] =0;

ind=384;

for (i=0;i<256; i++)

clp[ind++]=i;

ind=640;

for (i=0;i<384;i++)

clp[ind++]=255;

}

//

// Convert from YUV420 to RGB24

//

void ConvertYUV2RGB(unsigned char *src0,unsigned char *src1,unsigned char *src2,unsigned char *dst_ori,

int width,int height)

{

int y1,y2,u,v;

unsigned char *py1,*py2;

int i,j, c1, c2, c3, c4;

unsigned char *d1, *d2;

py1=src0;

py2=py1+width;

d1=dst_ori;

d2=d1+3*width;

for (j = 0; j < height; j += 2) {

for (i = 0; i < width; i += 2) {

u = *src1++;

v = *src2++;

c1 = crv_tab[v];

c2 = cgu_tab[u];

c3 = cgv_tab[v];

c4 = cbu_tab[u];

//up-left

y1 = tab_76309[*py1++];

*d1++ = clp[384+((y1 + c1)>>16)];

*d1++ = clp[384+((y1 - c2 - c3)>>16)];

*d1++ = clp[384+((y1 + c4)>>16)];

//down-left

y2 = tab_76309[*py2++];

*d2++ = clp[384+((y2 + c1)>>16)];

*d2++ = clp[384+((y2 - c2 - c3)>>16)];

*d2++ = clp[384+((y2 + c4)>>16)];

//up-right

y1 = tab_76309[*py1++];

*d1++ = clp[384+((y1 + c1)>>16)];

*d1++ = clp[384+((y1 - c2 - c3)>>16)];

*d1++ = clp[384+((y1 + c4)>>16)];

//down-right

y2 = tab_76309[*py2++];

*d2++ = clp[384+((y2 + c1)>>16)];

*d2++ = clp[384+((y2 - c2 - c3)>>16)];

*d2++ = clp[384+((y2 + c4)>>16)];

}

d1 += 3*width;

d2 += 3*width;

py1+= width;

py2+= width;

}

}

上面是CPP函数定义，以下是头文件
分别实现YUV420TORGB24和RGB24TOYUV420的转换
#include<stdio.h>
// Conversion from RGB24 to YUV420
void InitLookupTable();
int ConvertRGB2YUV(int w,int h,unsigned char *rgbdata,unsigned int *yuv);
// Conversion from YUV420 to RGB24
void InitConvertTable();
void ConvertYUV2RGB(unsigned char *src0,unsigned char *src1,unsigned char *src2,unsigned char *dst_ori,
int width,int height);