How do I reduce image size without losing any quality

private void barBtnOpenPhotos_ItemClick(object sender, DevExpress.XtraBars.ItemClickEventArgs e)
        {
            // there is where the user load's images
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.Filter = "JPG|*.jpg|JPEG|*.jpeg|PNG|*.png|Tif|*.tif";
            ofd.Multiselect = true;
            ofd.ShowDialog();
            string[] files = ofd.FileNames;
            // here  i create adatagridview to load multiple images 
            DataGridViewImageColumn img = new DataGridViewImageColumn();
            img.HeaderText = "ImageSelect";
            img.Name = "PhotoImage";
            img.ImageLayout = DataGridViewImageCellLayout.Stretch;
            datagridview_Images.Columns.Add(img);
            //here i view images inside 
            datagridview_Images.Rows.Clear();
            foreach (string filename in files)
            {
                Image image = Image.FromFile(filename);
//this is the method that's resize images
                image = reesizeImage(image, new Size(1024, 576)); 
                datagridview_Images.Rows.Add(image);
            }
        }
private static Image reesizeImage(Image imgToResize, Size size)
        {
            int sourceWidth = imgToResize.Width;
            int sourceHeight = imgToResize.Height;

            float nPercent = 0;
            float nPercentW = 0;
            float nPercentH = 0;

            nPercentW = ((float)size.Width / (float)sourceWidth);
            nPercentH = ((float)size.Height / (float)sourceHeight);

            if (nPercentH < nPercentW)
                nPercent = nPercentH;
            else
                nPercent = nPercentW;

            int destWidth = (int)(sourceWidth * nPercent);
            int destHeight = (int)(sourceHeight * nPercent);

            Bitmap b = new Bitmap(destWidth, destHeight);
            Graphics g = Graphics.FromImage((Image)b);
            g.InterpolationMode = InterpolationMode.HighQualityBicubic;

            g.DrawImage(imgToResize, 0, 0, destWidth, destHeight);
            g.Dispose();

            return (Image)b;
        }