Bitmap bmOld = new Bitmap(strOldFilePath);
                int iwidth = bmOld.Width;
                int iHeight = bmOld.Height;                Bitmap bmNew = new Bitmap(iwidth, iHeight, PixelFormat.Format16bppRgb565);
                Graphics g = Graphics.FromImage(bmNew);
                g.DrawImage(bmOld, new Point(0,0));
                g.Dispose();
                //bmNew.Save(strNewFilePath, ImageFormat.Bmp);                MessageBox.Show(bmOld.PixelFormat.ToString());
                MessageBox.Show(bmNew.PixelFormat.ToString());网上有这种方法,但如果我把新的bitmap保存后,重新打开,再显示它的PixelFormat,则会变成Format32rgb了.