Develop Reference

C# .Net Emgu.CV is inconsistently transferring bytes to itself

I'm using Emgu.CV to templateMatch and to save Images.
Unfortunetly I have ran into an issue that I have no been able to solve for a weeks.
Problem is that i serialize byte array and size from original Image to json file, and whenever i try to convert it back sometimes the image is distorted.
I have already tried skipping over serializing procces and it still became distorted.
Here is code of converting procces:
Image<Bgr565, byte> screenCrop = SnipMaker.takeSnip();//method creates screenshot at this point when i display the images they are 100% correct
byte[] data = screenCrop.Bytes;//I would get normaly all this from json file(in this case im skipping over it)
Mat mat = new Mat(screenCrop.Rows, screenCrop.Cols, screenCrop.Mat.Depth, asset.NumberOfChannels);
Marshal.Copy(data, 0, mat.DataPointer, screenCrop.asset.Cols * screenCrop.asset.Rows * asset.NumberOfChannels);
Image<Bgr565, byte> img = mat.ToImage<Bgr565, byte>();//This image is suddenly distorted
Problem is that this results depending on "I'm not sure what" is either prefecly good image or skwed one:
normal result
same code different result
Its almost like its sometimes 1 pixel behind but only thing that is changing is size and dimentions of screen shots.
I have tried dirrect ways like
Image<Bgr, byte> img = new Image<Bgr, byte>(width, height);
img.Bytes = data;//data is byte array that i got from file
This also gives sometimes correct picture but other times it throws an exeption (out of range exception in marshal.cs when trying to copy bytes from data to img)
only thing that i suspect at this point is that im doing something wrong whenever im taking screenshot but im not sure what:
public static Image<Bgr565, byte> Snip()
{
int screenWidth = (int)System.Windows.SystemParameters.PrimaryScreenWidth;
int screenHeight = (int)System.Windows.SystemParameters.PrimaryScreenHeight;
using (Bitmap bmp = new Bitmap(screenWidth, screenHeight))
{
using (Graphics gr = Graphics.FromImage(bmp))
gr.CopyFromScreen(0, 0, 0, 0, bmp.Size);
using (var snipper = new SnippingTool(bmp))
{
if (snipper.ShowDialog() == true)
{
Bitmap bitmapImage = new Bitmap(snipper.Image);
Rectangle rectangle = new Rectangle(0, 0, bitmapImage.Width, bitmapImage.Height);//System.Drawing
BitmapData bmpData = bitmapImage.LockBits(rectangle, ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format24bppRgb);//System.Drawing.Imaging
Image<Bgr565, byte> outputImage = new Image<Bgr565, byte>(bitmapImage.Width, bitmapImage.Height, bmpData.Stride, bmpData.Scan0);
bitmapImage.Dispose();
snipper.Close();
return outputImage;
}
}
return null;
}
}
So far I have not been able to solve this and knowing my luck noone will proppably anwser me here. But please could someone help me with this?
Thank you in advance

So thank you to everyones help.
The issue was indeed in the screenshot script. I've used incorrect combination of
pixel formats which resulted in inconsistent bit transfer.
But because the step property in Image<bgr,byte>.Mat was calculated based on the width of the image (Emgucv SC):
step = sizeof(byte) * s.Width * channels;
It caused that some of the images looked normal and other didn't.(speculation based on observation)
Fix:
change all Image<Bgr, byte> to Image<Bgra, byte>
to make it 32bit and then change:
BitmapData bmpData = bitmapImage.LockBits(rectangle, ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
to:
BitmapData bmpData = bitmapImage.LockBits(rectangle, ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format32bppRgb);
Hope this will help someone in the future. : )

Windows Store App - WriteableBitmap , blit method

Alright , i am trying to merge two images(superimpose one image on top of another) using writeablebitmapex library's blit method. And after applying the blit all i am getting is a transparent image with no content.
I would like to superimpose the curtain image on top of the window image.
Source Code :
WriteableBitmap photoWriteableBitMap = await new WriteableBitmap(1,1).FromContent(new Uri("ms-appx:///Curtain1.jpg"));
WriteableBitmap frameWriteableBitMap = await new WriteableBitmap(1, 1).FromContent(new Uri("ms-appx:///Window1.jpg"));
var merge = new WriteableBitmap(750, 750);
merge.Blit(new Rect(0, 0, 100, 100), photoWriteableBitMap, new Rect(0, 0, photoWriteableBitMap.PixelWidth, photoWriteableBitMap.PixelHeight));
merge.Blit(new Rect(0, 0, 200, 200), frameWriteableBitMap, new Rect(0, 0, frameWriteableBitMap.PixelWidth, frameWriteableBitMap.PixelHeight));
// Assign the merged writeable bitmap to the image source.
imgMain.Source = merge;
Expected Image :
Actual Image :
Please let me know what i am doing wrong.

I have found an answer to my solution in case anyone stumbles upon here.
First thing , I was unnecessarily trying to include an extra bitmap(merge) for the desired output.
All I had to do was apply the blit on the window image and set the source and the destination rectangles appropriately.
Below is the final code which works for me ,
WriteableBitmap photoWriteableBitMap = await new WriteableBitmap(1, 1).FromContent(new Uri("ms-appx:///Curtain1.jpg"));
WriteableBitmap frameWriteableBitMap = await new WriteableBitmap(1, 1).FromContent(new Uri("ms-appx:///Window1.jpg"));
frameWriteableBitMap.Blit(new Rect(300, 100, 250, 200), photoWriteableBitMap, new Rect(0, 0, photoWriteableBitMap.PixelWidth , photoWriteableBitMap.PixelHeight));
This is how my final image looks :

ArgumentException when initialising WriteableBitmap

I'm trying to write a simple program in WPF where the entire window is taken up by an image whose source is a WriteableBitmap that I draw. Here is the relevant code:
var image = m_Window.CustomImage;
image.Source = new WriteableBitmap(
(int) image.ActualWidth,
(int) image.ActualHeight,
300,
300,
PixelFormats.Bgra32,
null
);
but when I run this I get System.ArgumentException: Value does not fall within the expected range on the constructor. Frustratingly it does not say which value is incorrect. I have tried googling but there have been precious few examples of a WriteableBitmap constructor, and those that do exist are what generated the above code in the first place. Any advice?

The problem is that the ActualWidth and ActualHeight properties of image are 0, which will cause the ArgumentException.
Try setting the values of the values of the pixelWidth and pixelHeight properties to positive integers and see if the exception goes away.
image.Source = new WriteableBitmap(
300,
300,
300,
300,
PixelFormats.Bgra32,
null
);

WriteableBitmap crashes program with no message?

I create a WriteableBitmap object, draw a line and try to set it as the source to an Image control. For some reason, the program stops responding and then closes 5 seconds later when I try to set the Source. Anyone have any idea what's wrong? (I am also using WriteableBitmapEx)
WriteableBitmap bit = new WriteableBitmap(400, 400, 96, 96, PixelFormats.Bgr32, null);
WriteableBitmapExtensions.DrawLine(bit, 10, 10, 300, 300, Core.PrimaryColor.ColorValue);
ImageCanvas.Source = bit; // Sets the image to our bitmap, but program crashes for some reason!

When I try your code, it throws an ArgumentException saying
The input WriteableBitmap needs to have the Pbgra32 pixel format. Use
the BitmapFactory.ConvertToPbgra32Format method to automatically
convert any input BitmapSource to the right format accepted by this
class.\r\nParametername: writeableBitmap
Hence this works:
var bitmap = new WriteableBitmap(400, 400, 96, 96, PixelFormats.Pbgra32, null);
WriteableBitmapExtensions.DrawLine(bitmap, 10, 10, 300, 300, Colors.Black);
image.Source = bitmap;
UPDATE: As noted by Anders, you should perhaps use the portable bitmap factory method provided by WriteableBitmapEx to create your bitmap:
var bitmap = BitmapFactory.New(400, 400);
WriteableBitmapExtensions.DrawLine(bitmap, 10, 10, 300, 300, Colors.Black);
image.Source = bitmap;

How do I fill a rectangle with the exception of a area

I am trying to fill a rectangle in a winforms application less a ellipse in the center that allows the image in the background to show through.
can anyone give me a hint on which way to go on this,
thanks.
this is what I have come up with so far:
path.AddRectangle(new Rectangle(30, 30, 100, 100));
path.AddEllipse(new Rectangle(50, 50, 60, 60));
gfx.FillPath(new SolidBrush(Color.Black), path);

protected override void OnPaint(PaintEventArgs e){
var rgn = new Region(new Rectangle(50, 50, 200, 100));
var path = new GraphicsPath();
path.AddEllipse(60, 60, 180, 80);
rgn.Exclude(path);
e.Graphics.FillRegion(Brushes.Blue, rgn);
}

The easy way:
Fill the Reacngle first
Then Fill the Ellipse (with a Transparant brush)

It isn't clear enough what kind of transparency is required there. The simple way is to invert the problem. Use a TextureBrush to draw the image with Graphics.FillEllipse().

You could try to use regions. Create a rectangle region, exclude an ellipse and then fill it.