Retrieve EntityImage url in mscrm 2013

First you need to get the service object

to get service object follow the below link:
http://raju2565.blogspot.in/2014/07/mscrm-online-authentication.html


       Entity _account = new Entity("account");
        //Retrieve and the records with just the url
        string imageUrlQuery = String.Format(@"<fetch mapping='logical'>
                          <entity name='{0}'>
                            <attribute name='sample_name' />
                            <attribute name='entityimage_url' />
                          </entity>
                          </fetch>", _account);

        EntityCollection imageUrlResults = service.RetrieveMultiple(new FetchExpression(imageUrlQuery));


        Console.WriteLine("These are the relative URLs for the images retrieved:");
        foreach (Entity record in imageUrlResults.Entities)
        {
            String imageUrl = record["entityimage_url"] as String;
            Console.WriteLine(imageUrl);
        }