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Android doesn't support .NET framework so you cannot do this native. You would have to create or make use of another third framework to connect them. ASP.NET is a very useful candidate for this.
You can create a simple website in ASP.NET, no matter which framework (MVC or Web API) and use it as the client for your Web Service. Then, upload the image from that website (probably using a browser) and it would be uploaded to your hub (of your WCF application).