private void btnAuthenticate_Click(object sender, EventArgs e)
        {
            try
            {
                var predictedUserId = _recognizerEngine.RecognizeUser(new Image <Gray, byte>(picCapturedUser.Image.Bitmap));
                if (predictedUserId == -1)
                {
                    MessageBox.Show("This person is not recognized, Kindly register this face", "Authentication Result",
                                    MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
                else
                {
                    //proceed to documents library
                    IDataStoreAccess dataStore = new DataStoreAccess(_databasePath);
                    var username = dataStore.GetUsername(predictedUserId);
                    if (username != String.Empty)
                    {
                        int count = dataStore.CheckWithCourse(username);
                        if (count >= 1)
                        {
                            DialogResult result = MessageBox.Show("Student recognized as " + username + ". Is your Username " + username + "?", "Confirm your identity", MessageBoxButtons.YesNo, MessageBoxIcon.Question);

                            if (result == DialogResult.Yes)
                            {
                                int count2 = dataStore.CheckIfAlreadyExists(username);
                                if (count2 >= 1)
                                {
                                    MessageBox.Show("Username " + username + " is already marked present in today's class");
                                }
                                else
                                {
                                    string output = dataStore.MarkAttendance(username);
                                    if (output == "successful")
                                    {
                                        MessageBox.Show("Attendance marked successful for " + username + ". Also an email is sent to your email address showing Attendance Confirmation");
                                    }
                                    else
                                    {
                                        MessageBox.Show("Attendance not marked since some error occured");
                                    }
                                }
                            }
                        }
                        else
                        {
                            MessageBox.Show("Student Recognized as " + username + " but this student is not enrolled in this course");
                        }
                    }
                    else
                    {
                        MessageBox.Show("No Username for this face, Kindly register this face", "Authentication Result",
                                        MessageBoxButtons.OK, MessageBoxIcon.Error);
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error: " + ex.Message, "Authentication Result - Error", MessageBoxButtons.OK,
                                MessageBoxIcon.Error);
            }
        }