public byte[] getImageFromUrl(string url)
    {
        System.Net.HttpWebRequest request = null;
        System.Net.HttpWebResponse response = null;
        byte[] b = null;

        request = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(url);
        response = (System.Net.HttpWebResponse)request.GetResponse();

        if (request.HaveResponse)
        {
            if (response.StatusCode == System.Net.HttpStatusCode.OK)
            {
                Stream receiveStream = response.GetResponseStream();
                using (BinaryReader br = new BinaryReader(receiveStream))
                {
                    b = br.ReadBytes(500000);
                    br.Close();
                }
            }
        }

        return b;
    }

This snippet pulls down an image from a URL into a byte().  From there you can re-size or save. 

Don't forget the necessary try - catch.

Pull Image into Byte Array from a URL

url, image

C#