You need an 11-pin MHL adapter to get HDMI out. Alternatively you can combine a 5-pin to 11-pin adapter and a regular 5-pin MHL adapter for HDMI out.
Thanks for your response.
I dont expect there to be a dedicated port because even the EVO LTE doesnt have it, however, the EVO LTE has this:
(the EVO LTE has a specialized micro USB port with MHL technology (Mobile High Definition Link).
MHL allows high definition video output through the Micro USB port. A growing number of new TV’s are shipping with an MHL input on them. If you don’t have a compatible TV, there are special cables/ adapters made that convert Micro USB MHL to HDMI, allowing you to connect your phone to your HDTV.)
So my question is , does the galaxy S 3 have MHL technology?
I got the information from http://androidforums.com/htc-evo-4g-lte/529291-official-htc-evo-4g-lte-faq-guide.html
Here is an example of what you would need to buy. I hope that helps, and from reading the reviews Samsung may have made it propiertary. Or at least made it difficult to make a generic version of their adapter.