Load an image in hard disk using OpenCV and Qt - image

Question

I am new using Qt and OpenCV.
I am trying to read an image in my HD and show it.
It is not a specific image, the program could read any image that user select.
My code:
QString Imagename = QFileDialog::getOpenFileName(
this,
tr("Open Images"),
"C://",
tr("Tiff Files (*.tif);; Raw file (*.raw)"));
if ( Imagename.isNull())
{
QMessageBox::warning(this,"Error!","Image not valid!");
}
cv::Mat src(filename);
Mat configuration is:
Mat imread(const string& filename, int flags=1 )
How can I solve this?

Answer 1

cv::Mat doesn't have a contructor that accepts a string. Use imread instead. Since imread accepts std::string, not QString, just do:
cv::Mat yourImage = cv::imread(filename.toStdString());

Answer 2

You cannot use cv::Mat variable as you used.To solve this problem you should use "imread" function.I think following code will help you about this issue. You have to include following libraries.
#include<QFileDialog>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>
int main (){
// Gets file name with QFileDialog
QString file_name=QFileDialog::getOpenFileName(this,"Open Image File","C://","Image File (*.jpg *.tiff *.png *.bmp)");
// Read image with Color Image Parameter and store on image variable which type is cv::Mat
// You should convert file name from QString to StdString to use in imread function
cv::Mat image = cv::imread(file_name.toStdString(),CV_LOAD_IMAGE_COLOR);
if(!image.data){ // Checks whether the image was read successfully
qDebug()<< "Could not open or find the image";
return -1;
}
cv::namedWindow("Original Image",WINDOW_AUTOSIZE); // Creates a window which will display image
cv::imshow("Original Image",image); // Shows image on created window
cv::waitKey(0); // Waits for a keystroke in the window
return 0; // if you created console app in qt you should use return a.exec() instead of this.
}