UCService.ImageView img = serviceClient.ImageGetById("10020", new UCService.ImageSize()
{ 
    Width = 4096, 
    Height = 4096 
});

Image1.ImageUrl = "data:image/jpeg;base64," + img.Image;

System.Drawing.Image im = System.Drawing.Image.FromStream(new MemoryStream(Convert.FromBase64String(img.Image)));
im.Save(@"c:\temp\img999.bmp");