DoCoMoの絵文字を別の文字に変換する

DoCoMoの絵文字コード一覧はこちら
http://www.nttdocomo.co.jp/service/imode/make/content/pictograph/basic/index.html
http://www.nttdocomo.co.jp/service/imode/make/content/pictograph/extention/index.html

private string EmojiConvert(string input)

{

	StringBuilder sb = new StringBuilder();

	Encoder enc = Encoding.GetEncoding("Shift_JIS").GetEncoder();

	for(int i = 0; i < input.Length; i++)

	{

		char c = input[i];

		

		byte[] rawData = new byte[2];

		enc.GetBytes(new char[]{c},0,1,rawData,0,true);
		string strCode = rawData[0].ToString("X2") + rawData[1].ToString("X2");

		int charCode =  Convert.ToInt32( strCode,16);

		string s = null;

		

		if( (charCode >= 0xF89F && charCode <= 0xF95E) 

			||  (charCode >= 0xF9B1 && charCode <= 0xF9FC))

		{

			s = "絵文字";

		}

		else

		{

			s = c.ToString();

		}
		sb.Append(s);

		

	}	

	return sb.ToString();

}