gistfile1.cs

public class PngProcessor : MediaTypeProcessor
{
    public PngProcessor(HttpOperationDescription operation, 
                        MediaTypeProcessorMode mode) : base (operation, mode)
    {
    }
    
    public override IEnumerable< string > SupportedMediaTypes
    {
        get
        {
            yield return "image/png";
        }
    }
    
    public override void  WriteToStream(object instance,
                                        Stream stream,
                                        HttpRequestMessage request) 
    {                                      
        var contact = instance as Contact;
        
        if (contact != null)
        {
          var path = string.Format(CultureInfo.InvariantCulture, 
                                  @"{0}bin\Images\Image{1}.png",
                                  AppDomain.CurrentDomain.BaseDirectory,
                                  contact.ContactId);
                                  
            using (var fileStream = new FileStream(path, FileMode.Open))
            {
                byte[] bytes = new byte[fileStream.Length];
                fileStream.Read(bytes, 0, (int)fileStream.Length);
                stream.Write(bytes, 0, (int)fileStream.Length);
            }
        }
    }
    
    public override object ReadFromStream(Stream stream,
                                          HttpRequestMessage request)
    {
        throw new NotImplementedException();
    }
}