主题：知道二维码图片的base64数据（字符串值），能否转换为qrcode的字符串值？

Dim t As Table = Tables(e.Form.Name & "_FSCard")

If t.Rows.Count > 0 Then

    For Each r As Row In t.Rows

        If r("qrcode") > "" Then

        Else

            If r("img") > "" Then

                Dim bs As Byte() = Convert.FromBase64String(r("img"))

                Dim stream As System.IO.Stream = New System.IO.MemoryStream(bs)

                Dim bmp As System.Drawing.Bitmap = New System.Drawing.Bitmap(stream)

                Dim fl As String = ProjectPath & "fscard.jpg"

                bmp.save(fl)

                Application.DoEvents()

                If FileSys.FileExists(fl) Then

                    Dim img As Image = Image.FromFile(fl) '图片地址哦!

                    Dim bmap As Bitmap

                    bmap = New Bitmap(img)

                    Dim source As New RGBLuminanceSource(bmap, bmap.Width, bmap.Height)

                    Dim bitmap As com.google.zxing.BinaryBitmap = New com.google.zxing.BinaryBitmap(New com.google.zxing.common.GlobalHistogramBinarizer(source))

                    Dim asd As new com.google.zxing.MultiFormatReader

                    Dim result As com.google.zxing.Result = asd.decode(bitmap)

                    r("qrcode") = result.Text

                End If

            End If

        End If

        Application.DoEvents()

    Next

Else

    MessageBox.Show("当前表无记录!")

End If