VB2008 Inhalt aus gescannter PDF TIF erkennen

Imports System.Drawing.Imaging
Imports System.Runtime.InteropServices

Public Class Form1
    Private bm As Bitmap

    Protected Sub SetIndexedPixel(ByVal x As Integer, ByVal y As Integer, ByVal bmd As BitmapData, ByVal pixel As Boolean)
        Dim index As Integer = y * bmd.Stride + (x >> 3)
        Dim p As Byte = Marshal.ReadByte(bmd.Scan0, index)
        Dim mask As Byte = &H80 >> (x And &H7)
        If pixel Then
            p = p Or mask
        Else
            p = p And CByte(mask ^ &HFF)
        End If
        Marshal.WriteByte(bmd.Scan0, index, p)
    End Sub 'SetIndexedPixel  

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim X As Integer = 0
        Dim Y As Integer = 0
        Dim Schwellwert As Integer = 200
        Dim Farbe As Color
        Dim Wert1 As Integer = 0
        Dim Wert2 As Integer = 0
        Dim Wert1Check As Boolean = False
        Dim Wert2Check As Boolean = False

        Dim ofd As New OpenFileDialog
        ofd.InitialDirectory = "C:\Temp"  
        ofd.Filter = "JPG (*.jpg)|*.jpg| BMP (*.bmp)|*.bmp"  
        ofd.Title = "Wählen Sie eine Datei zum Öffnen aus"  
        If ofd.ShowDialog() = Windows.Forms.DialogResult.OK Then

            Dim img As Bitmap = CType(Image.FromFile(ofd.FileName), Bitmap)
            'Ensure that it's a 32 bit per pixel file  
            If img.PixelFormat <> PixelFormat.Format32bppPArgb Then
                Dim temp As New Bitmap(img.Width, img.Height, PixelFormat.Format32bppPArgb)
                Dim g As Graphics = Graphics.FromImage(temp)
                g.DrawImage(img, New Rectangle(0, 0, img.Width, img.Height), 0, 0, img.Width, img.Height, GraphicsUnit.Pixel)
                img.Dispose()
                g.Dispose()
                img = temp
            End If
            Me.PictureBox1.Image = img
            'lock the bits of the original bitmap  
            Dim bmdo As BitmapData = img.LockBits(New Rectangle(0, 0, img.Width, img.Height), ImageLockMode.ReadOnly, img.PixelFormat)

            'and the new 1bpp bitmap  
            bm = New Bitmap(Me.PictureBox1.Image.Width, Me.PictureBox1.Image.Height, PixelFormat.Format1bppIndexed)
            Dim bmdn As BitmapData = bm.LockBits(New Rectangle(0, 0, bm.Width, bm.Height), ImageLockMode.ReadWrite, PixelFormat.Format1bppIndexed)

            'scan through the pixels Y by   
            For Y = 0 To img.Height - 1
                For X = 0 To img.Width - 1
                    'generate the address of the colour pixel  
                    Dim index As Integer = Y * bmdo.Stride + X * 4

                    'check its brightness  
                    If Color.FromArgb(Marshal.ReadByte(bmdo.Scan0, index + 2), Marshal.ReadByte(bmdo.Scan0, index + 1), Marshal.ReadByte(bmdo.Scan0, index)).GetBrightness() > 0.5F Then
                        Me.SetIndexedPixel(X, Y, bmdn, True) 'set it if its bright.  
                    End If
                Next X
            Next Y

            'tidy up  
            bm.UnlockBits(bmdn)
            img.UnlockBits(bmdo)

            'display the 1bpp image  
            Me.PictureBox1.Image = bm


            For Y = 200 To 280 Step 1
                For X = 150 To 220 Step 1
                    Farbe = bm.GetPixel(X, Y)
                    If Farbe.Name = "ff000000" Then  
                        Wert1 += 1
                    End If
                Next X
            Next Y

            For Y = 300 To 360 Step 1
                For X = 150 To 220 Step 1
                    Farbe = bm.GetPixel(X, Y)
                    If Farbe.Name = "ff000000" Then  
                        Wert2 += 1
                    End If
                Next X
            Next Y

            If Wert1 > Schwellwert Then
                Wert1Check = True
            End If
            If Wert2 > Schwellwert Then
                Wert2Check = True
            End If

            Label1.Text = "Erste Box (Wert): " & Wert1 & " (" & Wert1Check & ")"  
            Label2.Text = "Zweite Box (Wert): " & Wert2 & " (" & Wert2Check & ")"  
            Label3.Text = "Schwellwert: " & Schwellwert  

        Else
            MsgBox("Abbruch")  
            Close()
            End
        End If
    End Sub
End Class