C# Image与Base64编码互转函数

public Bitmap GetImageFromBase64(string base64string)
        {
            byte[] b = Convert.FromBase64String(base64string);
            MemoryStream ms = new MemoryStream(b);
            Bitmap bitmap = new Bitmap(ms);
            return bitmap;
        }
public string GetBase64FromImage(string imagefile)
{
    string strbaser64 = "";
    try
    {
        Bitmap bmp = new Bitmap(imagefile);
        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();
        strbaser64 = Convert.ToBase64String(arr);
    }
    catch (Exception)
    {
        throw new Exception("Something wrong during convert!");
    }
    return strbaser64;
}