OpenFileDialog with Backgroundworker do work

I'm on WPF application and I'm using OpenFileDialog to load many images. At the same i'm calling many function to convert images based on selection of some checkBoxes. If i select 100 images it'll take approximately 1 minute to process, so I would like to handle it by 'BackGroundWorker _ doWork".

First I load the images to a temporary dir and apply some functions & then transfer images to another directory.

I don't know how can i handle this, please help me. Thank you.

	private void b35x5Files_Click(object sender, RoutedEventArgs e)
        {  bgw.RunWorkerAsync();

        }       

	   void bgw_DoWork(object sender, DoWorkEventArgs e)
        {
            var backgroundWorker = sender as BackgroundWorker;

            OpenFileDialog dialog = new OpenFileDialog();
            dialog.Filter = "Image files (*.jpg; *.jpeg; *.gif; *.tiff; *.png) | *.jpg; *.jpeg; *.gif; *.tiff; *.png";
            dialog.InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.MyPictures);
            dialog.Title = "Images";
            dialog.Multiselect = true;
            if (dialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)
            {
                int finalcountvalue = dialog.FileNames.Length + fileCount35x5;
                fileCount35x5 = dialog.FileNames.Length;
                foreach (string fileName in dialog.FileNames)//Copy files to a temp directory
                {
                    System.IO.File.Copy(fileName, tdestination_dir35x5 + @"\" + System.IO.Path.GetFileName(fileName), true);
                }


                fliptToVertical();// To change the image Orinetation

                if (c35x5ftimage.IsChecked == true)//CheckBox for AutoColorCorrection
                {
                    //MessageBox.Show("Hi, focker");

                }
                if (c35x5sepia.IsChecked == true)//CheckBox for Sepai Tone
                {
                    doSepia(destination_dir35x5);
                }
                if (c35x5grayscale.IsChecked == true)//CheckBox for GrayScale Tone
                {
                    doGrayScale(destination_dir35x5);
                }

                try // After finishing the above funciton move files to main directory
                {
                    foreach (string path in Directory.GetFiles(tdestination_dir35x5, "*.*",
                            SearchOption.TopDirectoryOnly))
                        File.Copy(path, path.Replace(tdestination_dir35x5, destination_dir35x5), true);
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.ToString());
                }

            }

        }

        void bgw_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            pbProcessing.Value = e.ProgressPercentage;
        }

        void bgw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            pbProcessing.Value = 100;
            MessageBox.Show("Finisheed ", "Completed", MessageBoxButton.OK, MessageBoxImage.Information);
        }