VS+QT+OpenCV
真费劲 忙活半天算是有效果了

#include "opencv2/opencv.hpp";
using namespace cv;

Demo1::Demo1(QWidget* parent)
	: QMainWindow(parent)
{
	ui.setupUi(this);
	connect(ui.btn, SIGNAL(clicked()), this, SLOT(Btn1Click()));
}


void Demo1::Btn1Click() {
	QString path = QFileDialog::getOpenFileName(this, "OpenCV打开PNG图片");
	String p = cv::format(path.toLocal8Bit());
	Mat  m = imread(p);
	imshow("opencvc", m);
}