MissionPlanner.Georefimage.WriteCoordinatesToImage C# (CSharp) Method

        void WriteCoordinatesToImage(string Filename, double dLat, double dLong, double alt)
        {
            using (MemoryStream ms = new MemoryStream(File.ReadAllBytes(Filename)))
            {
                TXT_outputlog.AppendText("GeoTagging "+ Filename + "\n");
                Application.DoEvents();

                using (Image Pic = Image.FromStream(ms))
                {
                    PropertyItem[] pi = Pic.PropertyItems;

                    pi[0].Id = 0x0004;
                    pi[0].Type = 5;
                    pi[0].Len = sizeof(ulong) * 3;
                    pi[0].Value = coordtobytearray(dLong);
                    Pic.SetPropertyItem(pi[0]);

                    pi[0].Id = 0x0002;
                    pi[0].Type = 5;
                    pi[0].Len = sizeof(ulong) * 3;
                    pi[0].Value = coordtobytearray(dLat);
                    Pic.SetPropertyItem(pi[0]);

                    pi[0].Id = 0x0006;
                    pi[0].Type = 5;
                    pi[0].Len = 8;
                    pi[0].Value = new Rational(alt).GetBytes();
                    Pic.SetPropertyItem(pi[0]);

                    pi[0].Id = 1;
                    pi[0].Len = 2;
                    pi[0].Type = 2;

                    if (dLat < 0)
                    {
                        pi[0].Value = new byte[] { (byte)'S', 0 };
                    }
                    else
                    {
                        pi[0].Value = new byte[] { (byte)'N', 0 };
                    }

                    Pic.SetPropertyItem(pi[0]);

                    pi[0].Id = 3;
                    pi[0].Len = 2;
                    pi[0].Type = 2;
                    if (dLong < 0)
                    {
                        pi[0].Value = new byte[] { (byte)'W', 0 };
                    }
                    else
                    {
                        pi[0].Value = new byte[] { (byte)'E', 0 };
                    }
                    Pic.SetPropertyItem(pi[0]);

                    // Save file into Geotag folder
                    string rootFolder = TXT_jpgdir.Text;
                    string geoTagFolder = rootFolder + Path.DirectorySeparatorChar + "geotagged";

                    string outputfilename = geoTagFolder + Path.DirectorySeparatorChar + Path.GetFileNameWithoutExtension(Filename) + "_geotag" + Path.GetExtension(Filename);

                    // Just in case
                    File.Delete(outputfilename);

                    Pic.Save(outputfilename);
                }
            }
        }