http://www.google.com/recaptcha/digitizing
以前很讨厌这套验证码系统，因为每次看着都很费劲，不过似乎不用全部输入正确也可以通过。
现在才知道原来是这么有意义而复杂的项目
Answers to reCAPTCHA challenges are used to digitize textual documents. It's not easy, but through a sophisticated combination of multiple OCR programs, probabilistic language models, and most importantly the answers from millions of humans on the internet, reCAPTCHA is able to achieve over 99.5% transcription accuracy at the word level. See for yourself!
以前很讨厌这套验证码系统，因为每次看着都很费劲，不过似乎不用全部输入正确也可以通过。
现在才知道原来是这么有意义而复杂的项目
Answers to reCAPTCHA challenges are used to digitize textual documents. It's not easy, but through a sophisticated combination of multiple OCR programs, probabilistic language models, and most importantly the answers from millions of humans on the internet, reCAPTCHA is able to achieve over 99.5% transcription accuracy at the word level. See for yourself!
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