【opencv源码解析】 二、 cvtColor

这里以CV_BGR2YUV_I420来讲

 

core.cpp

void cv::cvtColor( InputArray _src, OutputArray _dst, int code, int dcn )
{
  ...
case COLOR_RGB2YUV_YV12: case COLOR_BGR2YUV_YV12: case COLOR_RGBA2YUV_YV12: case COLOR_BGRA2YUV_YV12:
case COLOR_RGB2YUV_IYUV: case COLOR_BGR2YUV_IYUV: case COLOR_RGBA2YUV_IYUV: case COLOR_BGRA2YUV_IYUV:
if (dcn <= 0) dcn = 1;
uidx = (code == COLOR_BGR2YUV_IYUV || code == COLOR_BGRA2YUV_IYUV || code == COLOR_RGB2YUV_IYUV || code == COLOR_RGBA2YUV_IYUV) ? 1 : 2;
CV_Assert( (scn == 3 || scn == 4) && depth == CV_8U );
CV_Assert( dcn == 1 );
CV_Assert( sz.width % 2 == 0 && sz.height % 2 == 0 );
_dst.create(Size(sz.width, sz.height / 2 * 3), CV_MAKETYPE(depth, dcn));
dst = _dst.getMat();
hal::cvtBGRtoThreePlaneYUV(src.data, src.step, dst.data, dst.step, src.cols, src.rows,
scn, swapBlue(code), uidx);
break;

  ...
}

 

　　

color.cpp

void cvtBGRtoThreePlaneYUV(const uchar * src_data, size_t src_step,
uchar *