c# 使用队列保存图片

Invoke(new EventHandler(delegate
                        {
                           Bitmap bitmap2 = (Bitmap)eventArgs.Frame.Clone();
                            ThreadPool.QueueUserWorkItem(delegate
                                {
                                    bitmap2.Save(@"G:\VCAP\" + last.ToString("yyyy-MM-dd HH-mm-ss.fff") + @".jpg", ImageFormat.Jpeg);
                                    bitmap2.Dispose();
                                    bitmap2 = null;
                                });
                            GC.Collect();
                            pictureBox1.Image = bitmap;
                            pictureBox1.Refresh();
                            //Application.DoEvents();
                        }));