I want to ask which captcha service is a better? im using right now DBC, but it is not so good, can someone recommend better service for recaptchas 4x4?
Erm, see this from last week: http://www.scmagazine.com/security-researchers-defeat-recaptcha/article/488236/
"The researchers said the system they had devised was “extremely effective”, automatically solving 70.78 percent of the image reCaptcha challenges, while requiring only 19 seconds per challenge."
@happygeek - I read that as well. Here is Bruce Schneier's post about it last Friday: https://www.schneier.com/blog/archives/2016/04/breaking_semant.html
Basically, it all boils down to image analysis and pattern recognition. I used to do crude versions of this back when I was researching image processing algorithms (mid-1980's).
In which case have a keep it legal infraction, although I'm guessing it was just a spam thing anyway...