Get

For preservation's sake - here's the outline of what Jamie's blog said:

Use a Controller:

Get:

public HttpResponseMessage Get(int id)
{
    var result = new HttpResponseMessage(HttpStatusCode.OK);
    String filePath = HostingEnvironment.MapPath("~/Images/HT.jpg");
    FileStream fileStream = new FileStream(filePath, FileMode.Open);
    Image image = Image.FromStream(fileStream);
    MemoryStream memoryStream = new MemoryStream();
    image.Save(memoryStream, ImageFormat.Jpeg);
    result.Content = new ByteArrayContent(memoryStream.ToArray());
    result.Content.Headers.ContentType = new MediaTypeHeaderValue("image/jpeg");

    return result;
}

Delete

public void Delete(int id)
{
    String filePath = HostingEnvironment.MapPath("~/Images/HT.jpg");
    File.Delete(filePath);
}

Post

public HttpResponseMessage Post()
{
    var result = new HttpResponseMessage(HttpStatusCode.OK);
    if (Request.Content.IsMimeMultipartContent())
    {
        //For larger files, this might need to be added:
        //Request.Content.LoadIntoBufferAsync().Wait();
        Request.Content.ReadAsMultipartAsync<MultipartMemoryStreamProvider>(
                new MultipartMemoryStreamProvider()).ContinueWith((task) =>
        {
            MultipartMemoryStreamProvider provider = task.Result;
            foreach (HttpContent content in provider.Contents)
            {
                Stream stream = content.ReadAsStreamAsync().Result;
                Image image = Image.FromStream(stream);
                var testName = content.Headers.ContentDisposition.Name;
                String filePath = HostingEnvironment.MapPath("~/Images/");
                //Note that the ID is pushed to the request header,
                //not the content header:
                String[] headerValues = (String[])Request.Headers.GetValues("UniqueId");
                String fileName = headerValues[0] + ".jpg";
                String fullPath = Path.Combine(filePath, fileName);
                image.Save(fullPath);
            }
        });
        return result;
    }
    else
    {
        throw new HttpResponseException(Request.CreateResponse(
                HttpStatusCode.NotAcceptable,
                "This request is not properly formatted"));
    } 
}