QImage->cvMat:

Mat CameraThread::QImageTocvMat(QImage img)
{
	Mat ToCvMat;
	switch (img.format())
	{
	case QImage::Format_RGB888:
		ToCvMat = Mat(img.height(), img.width(), CV_8UC3, (void*)img.bits(), img.bytesPerLine());
		cv::cvtColor(ToCvMat, ToCvMat, CV_BGR2RGB);
		break;
	case QImage::Format_ARGB32:
	case QImage::Format_RGB32:
	case QImage::Format_ARGB32_Premultiplied:
		ToCvMat = Mat(img.height(), img.width(), CV_8UC4, (void*)img.bits(), img.bytesPerLine());
		break;
	case QImage::Format_Indexed8:
		ToCvMat = Mat(img.height(), img.width(), CV_8UC1, (void*)img.bits(), img.bytesPerLine());
		break;
	}
	return ToCvMat;
}

 

cvMat->QImage:

QImage CameraThread::cvMat2QImage(const cv::Mat& cvImg)
{
	QImage qImg;
	if (cvImg.channels() == 3)                             //三通道彩色影象
	{
		//CV_BGR2RGB
		cv::cvtColor(cvImg, cvImg, CV_RGB2BGR);
		qImg = QImage((const unsigned char*)(cvImg.data), cvImg.cols, cvImg.rows, cvImg.cols*cvImg.channels(), QImage::Format_RGB888);
	}
	else if (cvImg.channels() == 1)                    //單通道（灰度圖）
	{
		qImg = QImage((const unsigned char*)(cvImg.data), cvImg.cols, cvImg.rows, cvImg.cols*cvImg.channels(), QImage::Format_Indexed8);

		QVector<QRgb> colorTable;
		for (int k = 0; k<256; ++k)
		{
			colorTable.push_back(qRgb(k, k, k));
		}
		qImg.setColorTable(colorTable);//把qImg的顏色按畫素點的顏色給設定
	}
	else
	{
		qImg = QImage((const unsigned char*)(cvImg.data), cvImg.cols, cvImg.rows, cvImg.cols*cvImg.channels(), QImage::Format_RGB888);
	}
	return qImg;
}

 

QPixmap->QImage:

QPixmap pixmap;
QImage image=pixmap.toImage();

QImage->QPixmap:

QImage image;
QPixmap pixmap=QPixmap::fromImage(image);

原文：https://blog.csdn.net/weixin_39485901/article/details/88078406