Read an image with OpenCV in C++ and display it in C#

Question

I have a Mat in C++ which is presents my image.
I did some operation on in with OpenCV and now want to send it to my C# project and use it as an ImageSource.
But when I want to call the converter in c#, to convert it to ImageSource, I face to this error on bitmapObj.Save :

Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

my sample C++ source is:

Bitmap^ SomeClass::Test(System::String^ imgFileName)
{
   auto fileName = msclr::interop::marshal_as<string>(imgFileName);
   Mat img = imread(fileName);  
   auto bmp = gcnew Bitmap(img.cols, img.rows, img.step, Imaging::PixelFormat::Format24bppRgb, (IntPtr)img.data);
   img.release();
   return bmp;
}

and my sample c# code is:

private void ImageTester(object sender, RoutedEventArgs e)
{
    var image = testClass.Test("test.png");
    bg.Source = ConvertToBitmapImageFromBitmap(image);          
}   

public static BitmapImage ConvertToBitmapImageFromBitmap(Bitmap btm)
{
    using(var ms = new MemoryStream())
    {
        btm.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
        BitmapImage bImg = new BitmapImage();
        bImg.BeginInit();
        bImg.StreamSource = new MemoryStream(ms.ToArray());
        bImg.EndInit();
        return bImg;
    }
}

add a check for img.empty() after the imread(). you always have to check, when loading resources. — berak, Jul 16 '15 at 05:51
@berak : In fact I even saved it on hard by `imwrite` to make sure everything is all right. But still get the error. — Zhr Saghaie, Jul 16 '15 at 06:17
ok, sorry, did not read properly. - problem is , that your gcnew Bitmap does not copy the pixels. once you leave SomeClass::Test(), they are gone. — berak, Jul 16 '15 at 06:47
and it's strange that I can see width and height of the image in C# until exactly before .Save instruction. What's the reason of this one? — Zhr Saghaie, Jul 16 '15 at 08:26
The same reason and solution in this post: http://stackoverflow.com/a/31623351/2159536 — Zhr Saghaie, Jul 25 '15 at 05:46

Read an image with OpenCV in C++ and display it in C#

0 Answers0