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)

#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