Imports System.Drawing.Imaging
Imports System.Runtime.InteropServices
 
Public Class Form1
    Dim pixColor As Color
 
    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) _
      Handles Button1.Click
        Dim myColor As Color = Color.FromArgb(pixColor.ToArgb)
        PictureBox1.Image = ReplaceColor(Image.FromFile( _
          "c:\test\Muster01.jpg"), myColor, Color.Black)
    End Sub
 
    Public Function ReplaceColor(ByVal oBitmap As Image, ByVal OldColor As _
      Color, ByVal NewColor As Color) As Image
 
        Dim oMap(0) As ColorMap
        oMap(0) = New ColorMap
        With oMap(0)
            .OldColor = OldColor
            .NewColor = NewColor
        End With
 
 
        Dim oAttr As New ImageAttributes
        oAttr.SetRemapTable(oMap)
 
 
        Dim imgWidth As Integer = oBitmap.Width
        Dim imgHeight As Integer = oBitmap.Height
        Dim oImage As Image = Image.FromHbitmap( _
          New Bitmap(imgWidth, imgHeight).GetHbitmap)
 
 
        Using g As Graphics = Graphics.FromImage(oImage)
            g.DrawImage(oBitmap, New Rectangle(0, 0, imgWidth, imgHeight), _
              0, 0, imgWidth, imgHeight, GraphicsUnit.Pixel, oAttr)
        End Using
 
 
        Return oImage
    End Function
 
    Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) _
      Handles Button2.Click
        PictureBox1.Image = Image.FromFile("C:\test\Muster01.jpg")
 
    End Sub
    ' benötigte API-Funktionen
    <DllImport("gdi32.dll")> _
    Private Shared Function CreateDC( _
    ByVal lpszDriver As String, _
    ByVal lpszDevice As String, _
    ByVal lpszOutput As String, _
    ByVal lpInitData As IntPtr) As IntPtr
    End Function
 
    <DllImport("gdi32.dll")> _
    Private Shared Function DeleteDC(ByVal hdc As IntPtr) As Boolean
    End Function
 
    <DllImport("gdi32.dll")> _
    Private Shared Function GetPixel( _
    ByVal hdc As IntPtr, _
    ByVal nXPos As Integer, _
    ByVal nYPos As Integer) As Integer
    End Function
    Public Function GetPixelColor(ByVal x As Integer, ByVal y As Integer) As _
      Color
        Dim hdcScreen As IntPtr = CreateDC("Display", Nothing, Nothing, _
        IntPtr.Zero)
        Dim colorRef As Integer = GetPixel(hdcScreen, x, y)
        DeleteDC(hdcScreen)
 
        Return Color.FromArgb(colorRef And &HFF, _
          (colorRef And &HFF00) >> 8, (colorRef And &HFF0000) >> 16)
    End Function
 
    Private Sub PictureBox1_Click(sender As System.Object, e As _
      System.EventArgs) Handles PictureBox1.Click
        pixColor = GetPixelColor(Cursor.Position.X, Cursor.Position.Y)
        Label1.Text = pixColor.Name
        Label1.ForeColor = pixColor
    End Sub
 
    Private Sub PictureBox1_MouseHover(sender As Object, e As System.EventArgs) _
      Handles PictureBox1.MouseHover
        Me.Cursor = Cursors.Cross
    End Sub
 
    Private Sub PictureBox1_MouseLeave(sender As Object, e As System.EventArgs) _
      Handles PictureBox1.MouseLeave
        Me.Cursor = Cursors.Default
    End Sub
 
End Class