พอดีไปได้ Code Convert Text String to Image แต่ปัญหาคือหากเพิ่มข้อมูล

  Dim text As String = txtText.Text.Trim()
    Dim bitmap As New Bitmap(1, 1)
    Dim font As New Font("Arial", 25, FontStyle.Regular, GraphicsUnit.Pixel)
    Dim graphics As Graphics = graphics.FromImage(bitmap)
    Dim width As Integer = CInt(graphics.MeasureString(text, font).Width)
    Dim height As Integer = CInt(graphics.MeasureString(text, font).Height)
    bitmap = New Bitmap(bitmap, New Size(width, height))
    graphics = graphics.FromImage(bitmap)
    graphics.Clear(Color.White)
    graphics.SmoothingMode = SmoothingMode.AntiAlias
    graphics.TextRenderingHint = TextRenderingHint.AntiAlias
    graphics.DrawString(text, font, New SolidBrush(Color.FromArgb(255, 0, 0)), 0, 0)
    graphics.Flush()
    graphics.Dispose()
    Dim fileName As String = Path.GetFileNameWithoutExtension(Path.GetRandomFileName()) & ".jpg"
    bitmap.Save(Server.MapPath("~/images/") & fileName, ImageFormat.Jpeg)
    imgText.ImageUrl = "~/images/" & fileName
    imgText.Visible = True