转载-YUV422 to RGB565

原文：http://blog.csdn.net/skdev/article/details/4556760

/*------------------------
yuv422 to rgb565
转换公式：
R=Y+1.4075*(V-128)
G=Y-0.3455*(U-128) - 0.7169*(V-128)
B=Y+1.779*(U-128)
为了加快运算速度，采用下面的整形计算法：
u = YUVdata[UPOS] - 128;
v = YUVdata[VPOS] - 128;

rdif = v + ((v * 103) >> 8);
invgdif = ((u * 88) >> 8) +((v * 183) >> 8);
bdif = u +( (u*198) >> 8);

r = YUVdata[YPOS] + rdif;
g = YUVdata[YPOS] - invgdif;
b = YUVdata[YPOS] + bdif;
r=r>255?:255:(r<0:?0:r);
g=g>255?:255:(g<0:?0:g);
b=b>255?:255:(b<0:?0:b);
以上得到的是rgb888的数据，再将rgb888转为rgb555
RGBdata[1] =( (r & 0xF8) | ( g >> 5) );
RGBdata[0] =( ((g & 0x1C) << 3) | ( b >> 3) );
422 FORMAT size:
size=width*height*2;
YSIZE = size/2;
USIZE = size/4;
VSIZE = size/4;
YPOS=0;
UPOS=YPOS + size/2;
VPOS=UPOS + size/4;

--------------------------*/
int convertyuv422torgb565(unsigned char *inbuf,unsigned char *outbuf,int width,int height)
{
  int rows,cols,rowwidth;
  int y,u,v,r,g,b,rdif,invgdif,bdif;
  int size;
  unsigned char *YUVdata,*RGBdata;
  int YPOS,UPOS,VPOS;

  YUVdata = inbuf;
  RGBdata = outbuf;

  rowwidth = width>>1;
  size=width*height*2;
  YPOS=0;
  UPOS=YPOS + size/2;
  VPOS=UPOS + size/4;

  for(rows=0;rows<height;rows++)
  {
    for(cols=0;cols<width;cols++)
    {
 u = YUVdata[UPOS] - 128;
 v = YUVdata[VPOS] - 128;

 rdif = v + ((v * 103) >> 8);
 invgdif = ((u * 88) >> 8) +((v * 183) >> 8);
 bdif = u +( (u*198) >> 8);

 r = YUVdata[YPOS] + rdif;
 g = YUVdata[YPOS] - invgdif;
 b = YUVdata[YPOS] + bdif;
 r=r>255?255:(r<0?0:r);
 g=g>255?255:(g<0?0:g);
 b=b>255?255:(b<0?0:b);
   
 *(RGBdata++) =( ((g & 0x1C) << 3) | ( b >> 3) );
 *(RGBdata++) =( (r & 0xF8) | ( g >> 5) );

 YPOS++;     
 
 if(cols & 0x01)
 {
    UPOS++;
    VPOS++;     
 } 
    }
    if((rows & 0x01)== 0)
    {
 UPOS -= rowwidth;
 VPOS -= rowwidth;
    }
  }
  return 1;
}