Forcing sentence start with Capital letter

[koyauni]

I am making a auto conversion from Arabic script into Latin. Users will be able to cut and past Arabic based text into text area and click convert. I have made it work accept for one crucial thing. Since in Arabic based alphabet there is no distinguish between small and capital letters I am having problem to force the converted sentences starting with capital letters. I appreciate any help in this regard.
Project is based at
http://kurdan.org/converter/arablatin.php

An example such as
(... ئه‌سته‌مترین ئه‌گه‌ره‌کانی. فه‌رهه‌نگی) => will become (... estemtirín egerekaní. ferhengí)

I want that the word ferhengí or any word after (.) starts with a capital letter in this case . Ferhangí

Thanks