QT与OpenCV开发常用的图像格式转换函数：QImage转Mat、Mat转QImage、QImage转IplImage、IplImage转QImage

QT配合OpenCV完成图像处理时，经常使用QT显示OpenCV处理的图像数据，下面列出常用的一些转换函数，方便OpenCV与QT之间转换。

适用的OpenCV的版本：OpenCV3.X和OpenCV2.X版本。

(1) 将QImage图片转为opecv的qimage格式

IplImage *Widget::QImage_to_IplImage(const QImage * qImage)
{
    int width = qImage->width();
    int height = qImage->height();
    CvSize Size;
    Size.height = height;
    Size.width = width;
    IplImage *IplImageBuffer = cvCreateImage(Size, IPL_DEPTH_8U, 3);
    for (int y = 0; y < height; ++y)
    {
        for (int x = 0; x < width; ++x)
        {
            QRgb rgb = qImage->pixel(x, y);
            CV_IMAGE_ELEM( IplImageBuffer, uchar, y, x*3+0 ) = qBlue(rgb);
            CV_IMAGE_ELEM( IplImageBuffer, uchar, y, x*3+1 ) = qGreen(rgb);
            CV_IMAGE_ELEM( IplImageBuffe