Converting jpg to Byte

I have been successfully inserting images from a SQL database into Word documents for quite some time.
A new requirement has arisen where we now want to put signature images in the documents when they have been uploaded into the database. This also works but I have a problem when no signature file has been loaded into database.
What I would like to do here is insert a standard ‘blank’ image from a file rather than database. Below is the code I am currently using. Is what I am trying to do possible and if so - how?
Thanks in advance.

Public Function GetSignatureImage(ByVal CoachID As Integer) As Byte()
    Dim strBrandImage As Byte()

    Using myConnection As SqlConnection = New SqlConnection(ConfigurationManager.ConnectionStrings("ConnectionString").ConnectionString)
        Const SQL As String = "Select SignImage from DB WHERE ID = @ID"
        Dim myCommand As New SqlCommand(SQL, myConnection)

        myCommand.Parameters.AddWithValue("@ID", ID)
        Dim myReader As SqlDataReader = myCommand.ExecuteReader

        If myReader.Read Then
            If (myReader("SignImage")) Is System.DBNull.Value Then
                strBrandImage = Nothing
                strBrandImage = (myReader("SignImage"))
            End If
        End If
        If strBrandImage Is Nothing Then
            'Get image from a file and convert to byte - this is my problem
        End If
    End Using
    Return strBrandImage
End Function


Thanks for your request. You can use the following code to get file bytes:

byte[] imageBytes = File.ReadAllBytes(@"C:\Temp\test.jpg");

Hope this helps.
Best regards.