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YUV422与RGB互相转换

2014-05-28 09:35 218 查看


YUV422与RGB互相转换(经验证在IPNC与PC上都可以)

前一段时间在DM8168中进行颜色空间的转换,在网上找了些程序,自己也根据网上的改了下,由于能力问题,实在是不好意思说做了好几天才弄出来,主要是因为YUV<—>RGB有各种各样的转换公式。在多次的实验修改后,终于找到了对的公式,共享出来,以便需要的人选择。
在监控系统中大多采用YUV的颜色空间,原因不说了,网上搜YUV转RGB各种介绍。
在TI的视频英语达芬奇系列中(这里只测试了DVR、IPNC),
采用如下公式:
yCbCr<-->rgb

Y’ = 0.257*R' + 0.504*G' + 0.098*B' + 16

Cb' = -0.148*R' - 0.291*G' + 0.439*B' + 128

Cr' = 0.439*R' - 0.368*G' - 0.071*B' + 128

R' = 1.164*(Y’-16) + 1.596*(Cr'-128)

G' = 1.164*(Y’-16) - 0.813*(Cr'-128) - 0.392*(Cb'-128)

B' = 1.164*(Y’-16) + 2.017*(Cb'-128)
转换效果图如下



第一幅是原图YUV,第二幅是转为RGB后存为bmp,反转是因为BMP图像是从最下面一行开始存取的原因,最下面一副是转回YUV的图像。
代码如下,代码中YUV采用YUYVYUYV的格式,RGB为RGBRGBRGB.....
http://download.csdn.net/detail/guo8113/7318031(代码下载)

[cpp] view
plaincopy





#ifndef _RGB2YUV__

#define _RGB2YUV__

#include <iostream>

using namespace std;

#define TUNE(r) ( r < 0 ? 0 : (r > 255 ? 255 : r) )

static int RGB_Y[256];

static int RGBR_V[256];

static int RGBG_U[256];

static int RGBG_V[256];

static int RGBB_U[256];

static int YUVY_R[256];

static int YUVY_G[256];

static int YUVY_B[256];

static int YUVU_R[256];

static int YUVU_G[256];

static int YUVU_B[256];

static int YUVV_R[256];

static int YUVV_G[256];

static int YUVV_B[256];

static int coff_rv[256];

static int coff_gu[256];

static int coff_gv[256];

static int coff_bu[256];

//直接采用公式浮点计算方式

//仅RGB2YUV采用了查表法,所以有一部分表是没有用到的

void InitTable()

{

int i;

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

{

//初始化表,放大256倍

RGB_Y[i] = 298 * (i - 16);

RGBR_V[i] = 408 * (i - 128);

RGBG_U[i] = 100 * (128- i);

RGBG_V[i]= 208*(128-i);

RGBB_U[i] =517 * (i - 128);

//y=0.257*r+0.504*g+0.098*b+16

//u = -0.148*r - 0.291*g + 0.439*b + 128

//0.439*r - 0.368*g - 0.071*b + 128

YUVY_R[i]=66*i;

YUVY_G[i]=129*i;

YUVY_B[i]=25*i;

YUVU_R[i]=-38*i;

YUVU_G[i]=-74*i;

YUVU_B[i]=112*i;

YUVV_R[i]=112*i;

YUVV_G[i]=-94*i;

YUVV_B[i]=-18*i;

/*所用公式(此公式不适用)

*pRGB = (unsigned char)(1.0*y + 8 + 1.402*(v-128)); pRGB++; // r

*pRGB = (unsigned char)(1.0*y - 0.34413*(u-128) - 0.71414*(v-128)); pRGB++; // g

*pRGB = (unsigned char)(1.0*y + 1.772*(u-128) + 0); pRGB++ ;

*/

coff_rv[i] = (8+1.402*(i-128))*256;

coff_gu[i] = -0.34413*(i-128)*256;

coff_gv[i] = -0.71414*(i-128)*256;

coff_bu[i] = 1.772*(i-128)*256;

/*应该使用如下公式:

Y’ = 0.257*R' + 0.504*G' + 0.098*B' + 16

Cb' = -0.148*R' - 0.291*G' + 0.439*B' + 128

Cr' = 0.439*R' - 0.368*G' - 0.071*B' + 128(标红的两组公式是可逆的转换)

R' = 1.164*(Y’-16) + 1.596*(Cr'-128)

G' = 1.164*(Y’-16) - 0.813*(Cr'-128) - 0.392*(Cb'-128)

B' = 1.164*(Y’-16) + 2.017*(Cb'-128)

*/

}

}

void YUV2RGB422(unsigned char *pRGB, unsigned char *pYUV,int size)

{

unsigned char y, u, v,y1;

int r,g,b;

unsigned int i=0;

unsigned int loop = size>>1;

while(loop-- >0)

{

y = *pYUV; pYUV++;

u = *pYUV; pYUV++;

y1 = *pYUV;pYUV++;

v = *pYUV; pYUV++;

r = 1.164*(y-16) + 1.596*(v-128);

g = 1.164*(y-16) - 0.813*(v-128) - 0.392*(u-128);

b = 1.164*(y-16) + 2.017*(u-128);

*pRGB = TUNE(r);pRGB++;

*pRGB = TUNE(g);pRGB++;

*pRGB = TUNE(b);pRGB++;

r = 1.164*(y1-16) + 1.596*(v-128);

g = 1.164*(y1-16) - 0.813*(v-128) - 0.392*(u-128);

b = 1.164*(y1-16) + 2.017*(u-128);

*pRGB = TUNE(r);pRGB++;

*pRGB = TUNE(g);pRGB++;

*pRGB = TUNE(b);pRGB++;

}

}

//size 为图片的大小

void RGB2YUV422(unsigned char *pRGB, unsigned char *pYUV,int size)

{

unsigned char r,g,b,u,v,u1,v1,r1,g1,b1;

//unsigned char *YUVBuff;

//unsigned char* p;

//p = YUVBuff;//

int loop = size/2;

int i;

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

{

r = *pRGB; pRGB++;

g = *pRGB; pRGB++;

b = *pRGB; pRGB++;

r1 = *pRGB; pRGB++;

g1 = *pRGB; pRGB++;

b1 = *pRGB; pRGB++;

//new method --- right

int y = ((YUVY_R[r] + YUVY_G[g] + YUVY_B[b] + 128) >> 8) +16;

u = ((YUVU_R[r] + YUVU_G[g] + YUVU_B[b] + 128) >> 8) + 128;

v = ((YUVV_R[r] + YUVV_G[g] + YUVV_B[b] + 128) >> 8) + 128;

int y1 = ((YUVY_R[r1] + YUVY_G[g1] + YUVY_B[b1] + 128) >> 8)+16;

u1 = ((YUVU_R[r1] + YUVU_G[g1] + YUVU_B[b1] + 128) >> 8) + 128;

v1 = ((YUVV_R[r1] + YUVV_G[g1] + YUVV_B[b1] + 128) >> 8) + 128;

*pYUV++ = TUNE(y);

*pYUV++ =(TUNE(u)+TUNE(u1))>>1;

*pYUV++ = TUNE(y1);

*pYUV++ = TUNE(v);

}

}

void inline Yuv2RgbPixel(unsigned char y,unsigned char u,unsigned char v,

unsigned char* rgbPixel)

{

int r = (RGB_Y[y] + RGBR_V[v] + 128) >> 8;

int g = ((RGB_Y[y] + RGBG_V[v] +RGBG_U[u]+ 128)>>8 );

int b = ((RGB_Y[y] + RGBB_U[u]+128 )>>8);

*rgbPixel=TUNE(r);rgbPixel++;

*rgbPixel=TUNE(g);rgbPixel++;

*rgbPixel=TUNE(b);

}

void YUV2RGB(unsigned char *pRGB, unsigned char *pYUV,int size)//444

{

unsigned char y, u, v;

for(int i=0;i<size;i++)

{

y = *pYUV; pYUV++;

u = *pYUV; pYUV++;

v = *pYUV; pYUV++;

Yuv2RgbPixel(y,u,v,pRGB);

pRGB += 3;

}

}

void inline Rgb2YuvPiexl(unsigned char r,unsigned char g,unsigned char b,unsigned char* pYUV)

{

int y = ((YUVY_R[r] + YUVY_G[g] + YUVY_B[b] + 128) >> 8) + 16;

int u = ((YUVU_R[r] + YUVU_G[g] + YUVU_B[b] + 128) >> 8) + 128;

int v = ((YUVV_R[r] + YUVV_G[g] + YUVV_B[b] + 128) >> 8) + 128;

*pYUV = TUNEY(y);pYUV++;

//*pYUV = u < 0 ? 0 : (u > 255 ? 255 : u);pYUV++;

*pYUV =TUNE(u);pYUV++;

*pYUV = TUNE(v);

}

void RGB2YUV(unsigned char *pRGB, unsigned char *pYUV,int size)

{

unsigned char r,g,b,y,u,v;

for(int i=0;i<size;i++)

{

r = *pRGB; pRGB++;

g = *pRGB; pRGB++;

b = *pRGB; pRGB++;

Rgb2YuvPiexl(r,g,b,pYUV);

pYUV +=3;

}

}

#endif

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