public static void CropImageStreaming(Stream imgStr, int Width, int Height, string filename)
    {
        //creo il bitmap dallo stream
        System.Drawing.Image bmpStream = System.Drawing.Image.FromStream(imgStr);

        System.Drawing.Image imgPhoto = CropStreaming(bmpStream, Width, Height, AnchorPosition.Center);
        try
        {
            imgPhoto.Save(filename, ImageFormat.Jpeg); //ERRORE GDI+
            imgPhoto.Dispose();
        }
        catch
        {}
    }