使用GdPicture.NET可以不用創(chuàng)建PDF文件而直接獲取Tiff文件中的OCR，下面給出這一示例的代碼，適用于單頁或者多頁的Tiff文件。

》》》下載GdPicture.NET最新試用版

Private Declare Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" (ByVal hwnd As Integer, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, ByVal lpDirectory As String, ByVal nShowCmd As Integer) As Integer


    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim oGdPictureImaging As New GdPicture.GdPictureImaging
        oGdPictureImaging.SetLicenseNumber("XXXX") 'Replace XXXX by a valid or commercial KEY
        oGdPictureImaging.SetLicenseNumberOCRTesseract("XXXX") 'Replace XXXX by a valid or commercial KEY

        Dim sOCR As String
        Dim hFile As Integer
        Dim ImageID As Integer = oGdPictureImaging.CreateGdPictureImageFromFile("")
        Dim PageCount As Integer = 1


        If oGdPictureImaging.GetStat = GdPictureStatus.OK Then
            If oGdPictureImaging.TiffIsMultiPage(ImageID) Then
                PageCount = oGdPictureImaging.TiffGetPageCount(ImageID)
            End If

            If Dir(My.Application.Info.DirectoryPath & "\ocr.txt") <> "" Then Kill((My.Application.Info.DirectoryPath & "\ocr.txt"))
            hFile = FreeFile()
            FileOpen(hFile, My.Application.Info.DirectoryPath & "\ocr.txt", OpenMode.Append)

            For I As Integer = 1 To PageCount
                If I > 1 Then
                    oGdPictureImaging.TiffSelectPage(ImageID, I)
                End If
                oGdPictureImaging.OCRTesseractReinit()
                sOCR = oGdPictureImaging.OCRTesseractDoOCR(ImageID, TesseractDictionary.TesseractDictionaryEnglish, "C:\Program Files\GdPicture.NET\Redist\Commons\OCR", "")
                If oGdPictureImaging.GetStat <> GdPictureStatus.OK Then
                    MsgBox("Error on page " + Str(I) + ": " + oGdPictureImaging.GetStat.ToString)
                End If
                oGdPictureImaging.OCRTesseractClear()
                PrintLine(hFile, "OCR Page " + Str(I))
                PrintLine(hFile, "-------------------------------------------------------------------")
                PrintLine(hFile, sOCR)
            Next I

            FileClose(hFile)
            oGdPictureImaging.ReleaseGdPictureImage(ImageID)

            Call ShellExecute(Me.Handle.ToInt32, vbNullString, My.Application.Info.DirectoryPath & "\ocr.txt", "", "", 1)
        Else
            MsgBox("Can't open selected file !")
        End If
    End Sub