If this can be converted into a vector graphic, which it should, creating a poster sized copy ought to be possible. I will poke around in some software to see what can be done.
I hate to be the bearer of bad news, but bitmapped graphics can't be converted into vector graphics. It's physically impossible. The information just isn't there.
You can convert vector to bitmap, however.
Imagine if you could carry around a small 100x100 photo, turn it into a vector graphic, and then blow it up to a side-of-a-building mural size! It would be a revolution. Like being able to store the Library of Congress on a 1.44MB floppy disk.
Physically impossible.