Help assembling a character portrait sheet

I've looked around the internet for awhile now, however I haven't found anything that answers my question. 

Essentially I downloaded the character portraits from a game, however they came disassembled (not really sure how else to phrase that). For example they would look like this: 
My question is is there any program which would assemble these pieces into a complete portrait, or is there something that would allow me to do it easily without the need to manually piece it together.

Any help would be greatly appreciated.