CAPTCHA is one of the most commonly heard term for differentiating humans and robots. Google has made its API for the new reCAPTCHA available to the developers. This article is to give you an idea about CAPTCHA and its features.
A CAPTCHAs are designed based upon three different abilities - invariant recognition, segmentation and parsing.
Invariant recognition:
Whatever may be the degree of variation of the letters in a CAPTCHA, they should be recognisable. Practically, there are infinite number of ways, a human brain can recognize a particular character, which a computer cannot. Hence, CAPTCHAs are to be designed in such a way that a computer cannot recognise the variations in the characters of a CAPTCHA.
Segmentation:
All the characters in a CAPTCHA are to be segmented in such a way that no two characters merge with eachother, but they should be seeming so, where only a human can recognise the individual characeters.
Parsing:
Parsing through the characters of the CAPTCHA should be clear. For example, the letter 'm' should be designed in such a way that it can be parsed as 'm' but not two 'n's.
When such complexities are introduced into the text, the text becomes more to be recognised by a human being rather than a computer. The same method of CAPTCHA is being used by many of the websites over the internet. However, with the advent of Artificial Intelligence (AI), these kind of text CAPTCHAs can be solved with 99.8% accuracy by the computers. Hence, there has been several forms of CAPTCHAs that involved in different combinations, geometries and multiple words.
Google has introduced a new kind of CAPTCHA, which Google calls it reCAPTCHA. This CAPTCHA deals with perceiving images rather than text. In this kind of CAPTCHA, the user have to select the appropriate images based upon the instructions. For example, the website may instruct you to select the squares that contain vehicles or the squares that contain street signs. This kind of perception-based inputs from the user makes the computer smart in differentiating humans and computers.
Later, Google has introduced the new technology of Invisible reCAPTCHA, that serves the same purpose of reCAPTCHA. But, in this context, there is no need of selecting the square based upon the instructions. All that you need to do is just 'tick' the box I'm not a robot. Based upon the history of user activities, the computer itself differentiates human and robot. But, I still wonder, why do we need that 'tick' too!
In celebration of the 10th anniversary of CAPTCHA, on 10th June, Google made the API used to implement the reCAPTCHA available to the Android developers. Click here to get the instructions and usage of this API.
CAPTCHA is not a word, it's the acronym for Completely Automated Public Turing test to tell Computers and Humans Apart.
A CAPTCHAs are designed based upon three different abilities - invariant recognition, segmentation and parsing.
Invariant recognition:
Whatever may be the degree of variation of the letters in a CAPTCHA, they should be recognisable. Practically, there are infinite number of ways, a human brain can recognize a particular character, which a computer cannot. Hence, CAPTCHAs are to be designed in such a way that a computer cannot recognise the variations in the characters of a CAPTCHA.
Segmentation:
All the characters in a CAPTCHA are to be segmented in such a way that no two characters merge with eachother, but they should be seeming so, where only a human can recognise the individual characeters.
Parsing:
Parsing through the characters of the CAPTCHA should be clear. For example, the letter 'm' should be designed in such a way that it can be parsed as 'm' but not two 'n's.
When such complexities are introduced into the text, the text becomes more to be recognised by a human being rather than a computer. The same method of CAPTCHA is being used by many of the websites over the internet. However, with the advent of Artificial Intelligence (AI), these kind of text CAPTCHAs can be solved with 99.8% accuracy by the computers. Hence, there has been several forms of CAPTCHAs that involved in different combinations, geometries and multiple words.
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| Multiple word CAPTCHA |
Later, Google has introduced the new technology of Invisible reCAPTCHA, that serves the same purpose of reCAPTCHA. But, in this context, there is no need of selecting the square based upon the instructions. All that you need to do is just 'tick' the box I'm not a robot. Based upon the history of user activities, the computer itself differentiates human and robot. But, I still wonder, why do we need that 'tick' too!
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| Invisible reCAPTCHA |
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