怎么读取出TIFF图片 （130M左右），当做背景图使用的  求大神支招 谢谢

string impath = @"f:\1.tif";
            FileStream myfs = File.OpenRead(impath);
            byte[] B_Read = new byte[myfs.Length];
            myfs.Read(B_Read, 0, B_Read.Length);
            myfs.Close();
            Bitmap resultBitmap;
            try
            {
                using (MemoryStream ImageMS = new MemoryStream())
                {
                    ImageMS.Write(B_Read,0, B_Read.Length);
                     resultBitmap = new Bitmap(ImageMS);
                }
            }
            catch
            {
                resultBitmap=null;
            }
            pictureBox1.Image = resultBitmap;

为什么图片太大就读不出来