WPF Image gray scale in VB.NET

The code snippet in this article shows how to apply gray scale affects to images using WPF and VB.NET
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The FormatConvertedBitmap is used to apply formatting on images in WPF. The FormatConvertedBitmap.Source property is a BitmapImage that will be used in the formatting process.

This code creates a BitmapImage.

        Dim bitmap As New BitmapImage()
        bitmap.BeginInit()
        bitmap.UriSource = New Uri("C:\Books\Book WPF\How do I\ImageSample\ImageSample\Flower.JPG")
        bitmap.EndInit()

This code snippet creates a FormatConvertedBitmap from the BitmapImage created above.

        Dim grayBitmapSource As New FormatConvertedBitmap()
        grayBitmapSource.BeginInit()
        grayBitmapSource.Source = Bitmap

The DestinationFormat property of FormatConvertedBitmap is used to apply formatting on images. The follow code snippet sets the formatting of an image to gray. 

grayBitmapSource.DestinationFormat = PixelFormats.Gray32Float
grayBitmapSource.EndInit()


The complete source code looks like this.

 

   Private Sub GrayScaleButton_Click(ByVal sender As ObjectByVal e As RoutedEventArgs)
        ' Create a BitmapSource 
        Dim bitmap As New BitmapImage()
        bitmap.BeginInit()
        bitmap.UriSource = New Uri("C:\Books\Book WPF\How do I\ImageSample\ImageSample\Flower.JPG")
        bitmap.EndInit()

        ' Create a FormatConvertedBitmap 
        Dim grayBitmapSource As New FormatConvertedBitmap()
 
        ' BitmapSource objects like FormatConvertedBitmap can only have their properties 
        ' changed within a BeginInit/EndInit block. 
        grayBitmapSource.BeginInit()

        grayBitmapSource.Source = bitmap

        ' Key of changing the bitmap format is DesitnationFormat property of BitmapSource. 
        ' It is a type of PixelFormat. FixelFormat has dozens of options to set 
        ' bitmap formatting. 
        grayBitmapSource.DestinationFormat = PixelFormats.Gray32Float
        grayBitmapSource.EndInit()

        ' Create a new Image 
        Dim grayImage As New Image()
        grayImage.Width = 300
        ' Set Image source to new FormatConvertedBitmap 
        grayImage.Source = grayBitmapSource

        ' Add Image to Window

        LayoutRoot.Children.Add(grayImage)
    End Sub

How to Crop an Image in WPF?

CroppedBitmap is used to cropping an image. It takes a BitmapImage as source and a rectangle that you would like to crop.

The following code snippet crops and displays an image.

    Private Sub CropImageButton_Click(ByVal sender As ObjectByVal e As RoutedEventArgs)
        ' Create a BitmapImage 
        Dim bitmap As New BitmapImage()
        bitmap.BeginInit()
        bitmap.UriSource = New Uri("C:\Books\Book WPF\How do I\ImageSample\ImageSample\Flower.JPG")
        bitmap.EndInit()

        ' Create an Image 
        Dim croppedImage As New Image()
        croppedImage.Width = 200
        croppedImage.Margin = New Thickness(2)

        ' Create a CroppedBitmap from BitmapImage 
        Dim cb As New CroppedBitmap(DirectCast(bitmap, BitmapSource), New Int32Rect(20, 20, 100, 100))
        ' Set Image.Source to cropped image 
        croppedImage.Source = cb

        ' Add Image to Window

        LayoutRoot.Children.Add(croppedImage)
    End Sub

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