Found on:
https://stackoverflow.com/questions/891643/twitter-image-encoding-challenge
https://bitbucket.org/tkadlubo/circles.lua/

Info:
Okay, I'm late to the game, but nevertheless I made my project.
It's a toy genetic algorithm that uses translucent colorful circles to recreate the initial image.

Features:
    pure Lua. Runs anywhere where a Lua interpreter runs.
    uses netpbm P3 format
    comes with a comprehensive suite of unit tests
    preserves original image size

Mis-feautres:
    slow
    at this space constraints it preserves only the basic color scheme of the initial image and a general outline of few features thereof.