' Open a Stream and decode a PNG image


Dim imageStreamSource As New FileStream("smiley.png", FileMode.Open, FileAccess.Read, FileShare.Read)


Dim decoder As New PngBitmapDecoder(imageStreamSource, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default)


Dim bitmapSource As BitmapSource = decoder.Frames(0)





' Draw the Image


Dim myImage As New Image()


myImage.Source = bitmapSource


myImage.Stretch = Stretch.None


myImage.Margin = New Thickness(20)

Dim width As Integer = 128


Dim height As Integer = 128


Dim stride As Integer = width


Dim pixels(height * stride) As Byte


' Define the image palette


Dim myPalette As BitmapPalette = BitmapPalettes.Halftone256


' Creates a new empty image with the pre-defined palette


Dim image As BitmapSource = System.Windows.Media.Imaging.BitmapSource.Create( _


    width, height, 96, 96, PixelFormats.Indexed8, myPalette, pixels, stride)


Dim stream As New FileStream("new.png", FileMode.Create)


Dim encoder As New PngBitmapEncoder()


Dim myTextBlock As New TextBlock()


myTextBlock.Text = "Codec Author is: " + encoder.CodecInfo.Author.ToString()


encoder.Interlace = PngInterlaceOption.On


encoder.Frames.Add(BitmapFrame.Create(image))


encoder.Save(stream)