what is the software that can make a photograph out of small ones?

Question

it gathers small photos in order to form a big one. I saw a poster for Monaliza made up in the same way. if you look at it closely you could see that the poster formed out of small different photographs.

Answer 1

Here you go, this software does it:
http://www.arcsoft.com/en/products/photomontage/

FYI, it is called a "photo montage".