How do I read a CAPTCHA with Java?

I always hear that reading a CAPTCHA is impossible and so now I want to write an open source CAPTCHA reader in Java. Was wondering what I should be looking fo开发者_如何学Gor... any good books? Any ideas on where to start?

I know this is a bit over my head, but I am still going to at least try.

Have a look at JDownloader. Part of their code reads captchas.

I don't know any Java code on how to do this, but I do remember reading this paper on how to break some of the older Captcha variants. I don't know how applicable this is in modern Captchas, but some of the techniques here might be useful. Be warned - this is a pretty technical paper.

Also, you should probably be aware that the best known techniques for breaking Captchas these days are to give them to humans in exchange for some reward.