Image(支持 XML 序列化)，注意C#中原生的Image类是无法进行Xml序列化的

    /// <summary>
    /// Image(支持 XML 序列化)
    /// </summary>
    [XmlRoot("XmlImage")]
    public class XmlImage : IXmlSerializable
    {
        public System.Drawing.Image Image { get; set; }

        #region 构造函数

        public XmlImage()
        { }

        protected XmlImage(SerializationInfo info, StreamingContext context)
        { }
        #endregion 构造函数

        #region IXmlSerializable Members
        public XmlSchema GetSchema() => null;

        /// <summary>
        ///     从对象的 XML 表示形式生成该对象(反序列化)
        /// </summary>
        /// <param name="xr"></param>
        public void ReadXml(XmlReader xr)
        {
            if (xr.IsEmptyElement)
                return;
            xr.ReadToFollowing(nameof(XmlImage));
            Image = FromBase64String(xr.ReadElementContentAsString());
            xr.ReadEndElement();
        }

        /// <summary>
        ///     将对象转换为其 XML 表示形式(序列化)
        /// </summary>
        /// <param name="xw"></param>
        public void WriteXml(XmlWriter xw)
        {
            xw.WriteStartElement(nameof(XmlImage));
            xw.WriteValue(ToBase64String(Image, ImageFormat.Png));
            xw.WriteEndElement();
        }
        #endregion IXmlSerializable Members

        private static string ToBase64String(System.Drawing.Image img, ImageFormat format)
        {
            if (img != null)
            {
                using (var ms = new MemoryStream())
                {
                    img.Save(ms, format);
                    byte[] buffer = ms.ToArray();
                    return Convert.ToBase64String(buffer);
                }
            }
            return string.Empty;
        }

        private static System.Drawing.Image FromBase64String(string base64Str)
        {
            System.Drawing.Image img = null;
            using (var ms = new MemoryStream())
            {
                try
                {
                    var buffer = Convert.FromBase64String(base64Str);
                    ms.Write(buffer, 0, buffer.Length);
                    img = System.Drawing.Image.FromStream(ms);
                }
                catch
                {
                    // ignored
                }
            }
            return img;
        }
    }