Convert Topaz Sigweb sigstring to Base64

I am working on a mobile application(ionic) where there is a field for user's signature. Users needs to sign with their finger in canvas.

Now this application has web version, where they used topaz sigweb to do this. Now to save signature and to view in both ends i need some kind of conversion.

I checked sigweb's documentation, they save the signature in ASCHII hex format. I am not sure if they are using any kind of internal encryption or not because i can not convert the hex string to any valid base 64.

I am not sure if there are any other way to do that. If anyone has any idea please share.

Thanks in advance.