protected override void Serialize(Stream output, ExifData exifData)
 {
     var serializer = new DataContractSerializer(typeof(ExifData));
     var writer = XmlWriter.Create(output);
     serializer.WriteObject(writer, exifData);
     writer.Flush();
 }
 protected abstract void Serialize(Stream output, ExifData exifData);
 protected override void Serialize(Stream output, ExifData exifData)
 {
     if (output == null) throw new ArgumentNullException("output");
     var serializer = new DataContractJsonSerializer(typeof(ExifData));
     serializer.WriteObject(output, exifData);
 }