将检索到的Blob转换为base64 vb.net

Question

我正在尝试从oracle数据库中读取blob并将其转换为base64String，然后将其显示在我的网页中。从oracle读取工作正常并返回数据，但是将图像转换为base64会返回巨大的值（长度= 1 600 000及以上），无法转换为图像并显示在我的页面中（显示损坏的图标图像）。换句话说，我在我的代码中从互联网实现了base64String，一切正常......将blob转换为图像的最佳方法是什么？以下是我的代码：

 Dim Conn As String = ConfigurationManager.ConnectionStrings("connString").ConnectionString
        Dim cnnConnection As New OracleConnection(Conn)
        cnnConnection.Open()

        Dim cmd As New OracleCommand()
        cmd.Connection = cnnConnection
        cmd.CommandText = "SELECT d.document_file from T_library_documents d d.library_documents_id=64 ORDER BY d.DOCUMENT_NAME"
        cmd.CommandType = CommandType.Text

        Dim dr As OracleDataReader = cmd.ExecuteReader
        If dr.Read() Then

            Dim blob As OracleBlob = dr.GetOracleBlob(0)
            Dim byteArr As [Byte]() = New [Byte](blob.Length - 1) {}
            Dim i As Integer = blob.Read(byteArr, 0, System.Convert.ToInt32(blob.Length))
            blob.Close()
            cnnConnection.Close()

            Dim imageBase64 As String = Convert.ToBase64String(byteArr)
            Dim imageSrc As String = String.Format("data:image/gif;base64,{0}", imageBase64)
            img.Attributes("src") = imageSrc
        End If