Jdog - You are setting the image boundries, if the image is larger, OF COURSE IT WILL GET CUT OUT! It will have the upper left part of the picture you wanted.... 16384 pixels of upper-left rubbishness. You have to RESIZE the IMAGE. Also, I must point out your stupidity in asking what Gimp is when its mentioned and linked in the first post.
RIP, you can't upload a head yet. Forget it until you buy the game.
THP is probably Tori Head Previewer. But I haven't searched for that, so I might be wrong.