you cant "pull" a font out of a graphic unless you have the source file and you'll have to have the font to do that. so thats not really going to solve your problem...
if you just need individual alpha-channel graphics you can do a magic wand thing in photoshop and copy and paste that into a new file. or you can autotrace it in in illustrator (but that wont likely be as accurate as youd want)
but making an actual font is no simple task. i used to use fontographer several years back, but they dont make it anymore.
to my knowledge, all of the other existing font building applications will require you to build and import the characters as vector outlines (i.e. adobe illustrator or such)