Android : How To Send An Image Through HTTPPost?

I'm creating an activity which needs to upload an image to a webservice using their api. I found that if i use UrlEncodedFormEntity and send the image data through that. the webservice doesn't receive that. ( at least it will not be able to read that .) In fact if i add some vars to send with the image data ( like name of the file, filesize ) they can be read from the webservice but the image data still doesn't appear if i try to read it serverside.