Image (RTF data) to plain text string

I have table, in which RTF documents are stored in Image Data type column. Now i need to convert this RTF data to plain text in readable format using T-SQL only.
Existing code is using some DLL (RTF to TEXT), which is invoked using SP_OACreate and need to change as permission to execute SP_OACreate is revoked.
I did little search and i found couple of functions
sys.fn_varbintohexstr
sys.fn_sqlvarbasetostr
sys.fn_varbintohexsubstring
But could not get through.

Is it something like
- first i need to convert this to varbinary then hexstring then plain text
- If i convert this to varbinary and then to str using sys.fn_sqlvarbasetostr then it is in some format, which i can not use directly and again need to fomat to plain text (directly readable fomat)
- Is there any way to remove additional RTF details from this (like {
tf1ansiansicpg1252deff0{fonttbl{f0fswissfcharset0 Microsoft Sans Serif;})?
- Or is there way to extract the main text from this RTF?

Any idea/suggestion would be of great help.Thanks in advance