YUV420: text color

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Hello!
I use opencv-2.4.8
Before encode YUV420 buffer I have to add some information, e.g. timestamp.
Follow my code:

cv::Mat *_img[3];

_img[0] = new cv::Mat(encop.picHeight, encop.picWidth, CV_8UC1,
            reinterpret_cast<unsigned *="">(_src_mem.virt_uaddr));
_img[1] = new cv::Mat(encop.picHeight / 2, encop.picWidth / 2, CV_8UC1,
            reinterpret_cast<unsigned *="">(_src_mem.virt_uaddr +
                        _size));
_img[2] = new cv::Mat(encop.picHeight / 2, encop.picWidth / 2, CV_8UC1,
        reinterpret_cast<unsigned *="">(_src_mem.virt_uaddr +
                    _size + _size / 4));

CvScalar OCV::yuv_color(float red,
                        float green,
                        float blue)
{
    return cvScalar(0.299 * red + 0.587 * green + 0.114 * blue,
            -0.14713 * red - 0.28886 * green + 0.436 * blue,
            0.615 * red - 0.51499 * green - 0.10001 * blue);
}

const CvScalar color = OCV::yuv_color(6.0, 249.0, 223.0);

putText(*_img[0], _osd, cv::Point(20, 20), cv::FONT_HERSHEY_SIMPLEX,
                0.5, color, 0, 16);
putText(*_img[1], _osd, cv::Point(10, 10), cv::FONT_HERSHEY_SIMPLEX,
                0.25, color, 0, 16);
putText(*_img[2], _osd, cv::Point(10, 10), cv::FONT_HERSHEY_SIMPLEX,
                0.25, color, 0, 16);
 

Code work fine, but I have little proble:
1. I get green text if I use RGB color
2. I get magenta text if I use YUV color

How can control text color for YUV420?
Thank you and excuse my bad english.