What it is:
Pixelize is a program that will use many scaled down images to
try to duplicate, as closely as possible, another image.
Pixelize works by splitting up the image you want rendered (or
duplicated) into a grid of small rectangular areas. Each area
is analyzed, and replaced with an image chosen from a large
database of images. Pixelize tries to pick images that best
match each area.
To know more about;
To install in Ubuntu:
sudo apt-get install pixelize