C# 图片转为Base64

/// <summary>
/// 图片转Base64
/// </summary>
/// <param name="ImageFileName">图片的完整路径</param>
/// <returns></returns>
public static string ImgToBase64(string ImageFileName)
{
    try
    {
        Bitmap bmp = new Bitmap(ImageFileName);

        MemoryStream ms = new MemoryStream();
        bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
        byte[] arr = new byte[ms.Length];
        ms.Position = ;
        ms.Read(arr, , (int)ms.Length);
        ms.Close();
        return Convert.ToBase64String(arr);
    }
    catch (Exception)
    {
        return null;
    }
}