图片转换成bas位字符串e

public static string ImgToBase64String(string filepath)
        {
            try
            {
                Bitmap bmp = new Bitmap(filepath);
                MemoryStream ms = new MemoryStream();
                bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
                byte[] arr = new byte[ms.Length];
                ms.Position = 0;
                ms.Read(arr, 0, (int)ms.Length);
                ms.Close();
                string pic = Convert.ToBase64String(arr);
                return pic;

            }
            catch
            {
                return false.ToString();
            }
        }