How to send a bitmap to a web service rest

Hi , i’m trying to send a bitmap to a ws.

I have try this code.

 string uri = "";
 POSTContent emptyPost = POSTContent.CreateBinaryBasedContent(b.GetBitmap());
 var req = HttpHelper.CreateHttpPostRequest(uri, emptyPost, "image/bmp");

But it seems it doesn’t work.
Something arrive , but i cant recreate in a correct way my image in the ws.

Someone can help me?
Thanks in advance.