emgucv - C# - WPF/Xaml - EMGU Display image

Question

I have a C#/WPF program which use EMGU to manipule a 4K video (image per image). I am doing some operations on the image like rotation, crop … these operations are fast.

My problem is that it take a long time to display the image (40ms). If I add my operations to this time I have less than 20FPS. Displaying the image is 70% of the time.

I am using this code :

<Image x:Name="VideoWidget" Stretch="Uniform"/>

if (_cameraWritableBitmap == null || _cameraWritableBitmap.PixelWidth != width || _cameraWritableBitmap.PixelHeight != height)
{
    _cameraWritableBitmap = new WriteableBitmap(
        width,
        height,
        dpiX,
        dpiY,
        pixelFormat,
        null);

    _mainWindow.VideoWidget.Source = _cameraWritableBitmap;
    OnPropertyChanged("ZoomImage");
    OnPropertyChanged("ZoomScreen");
    OnPropertyChanged("IsZoomImageAlert");
    OnPropertyChanged("IsZoomScreenAlert");
}

timePrev = DateTime.Now.Ticks / TimeSpan.TicksPerMillisecond;

_cameraWritableBitmap.Lock();
_cameraWritableBitmap.WritePixels(new Int32Rect(0, 0, width, height), imgColor.Bytes, width * 4, 0);
//Marshal.Copy(imgColor.Bytes, 0, _cameraWritableBitmap.BackBuffer, imgColor.Bytes.Length);
//_cameraWritableBitmap.AddDirtyRect(new Int32Rect(0, 0, width, height));
_cameraWritableBitmap.Unlock();
Console.WriteLine("# ECRITURE " + (DateTime.Now.Ticks / TimeSpan.TicksPerMillisecond - timePrev));

Do you know a fastest way to display my image ?

Thank you,

Answer 1

Ok I have found the perfect solution.

1. I create the writable Bitmap
2. I create the EMGU image based on the writable bitmap buffer

Then In my process I have :

1. Get the gray image
2. Convert the gray image directly in the EMGU Image
3. Tell the writable bitmap the buffer is updated

Allocate variables :

             _cameraWritableBitmap = new WriteableBitmap(
                width,
                height,
                dpiX,
                dpiY,
                PixelFormats.Bgra32,
                null);

            _mainWindow.VideoWidget.Source = _cameraWritableBitmap;

            _cameraImageBuffer = new Image<Bgra, byte>(width, height, _cameraWritableBitmap.BackBufferStride, _cameraWritableBitmap.BackBuffer);

Convert gray to Color :

CvInvoke.CvtColor(imgGray, _cameraImageBuffer, Emgu.CV.CvEnum.ColorConversion.Gray2Bgra);

Update the screen :

_cameraWritableBitmap.Lock();
_cameraWritableBitmap.AddDirtyRect(new Int32Rect(0, 0, width, height));
_cameraWritableBitmap.Unlock();