VistaArc

Few days back I saw a really nice post of Nadim Jahangir about breaking captcha [Breaking CAPTCHA: Getting Naughty With Computer Vision Based Human Interaction Simulator Bot]. After, reading his post, I’d decided to create something similar with PHP. And I’ve already done it. I also use somewhereindhaka.net captcha for my experiment but didn’t create any bot to post in their site .

Steps are very simple -

1. Create horizontal & vertical histogram of captcha using PHP GD.
2. Recognize each character by comparing values from histogram.
3. I didn’t use any Template Recognition Algorithm. Rather, I use simple Edit Distance Algorithm (Levenshtein Distance). And it works

See it live – http://tr.im/35au