read Scan pdf document to text file in VB.NET

if it is text format,I readed it to text file but with scan fromat I can't. I tried using itextshap library in VB.NET to read but false.I hope that anybody can help me resolve this problem!

<pre><pre lang="vb">
Public Sub SubFoldersRecursive(ByVal Root As DirectoryInfo, ByRef Status As String)
Try
Status += Root.FullName + vbNewLine
If (Root.GetDirectories.Length <= 0) Then
Exit Sub
End If
Dim SD As DirectoryInfo
For Each SD In Root.GetDirectories
SubFoldersRecursive(SD, Status)
Next
Catch ex As Exception
Status += ex.Message + vbNewLine
End Try
End Sub
'NON-Recursive Function To Find All SubDirectory Names
Public Sub SubFolders(ByVal Root As DirectoryInfo, ByRef Status As String)
Dim Dir As DirectoryInfo
Status += Root.FullName + vbNewLine
For Each Dir In Root.GetDirectories("*", SearchOption.AllDirectories)
Status += Dir.FullName + vbNewLine
Next
End Sub




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