We have already written an article on the importance of having captcha on your website. However, with the increase in use of e-commerce business and hence captcha, spammers are working really hard to make it possible for them to write a bot which can bypass captcha also. This article covers something which you should keep in your mind to make sure that your captcha is safe and secure. The basic understanding of how computer will solve a captcha is must designing a captcha which can’t be cracked easily.

Any software solves any captcha or read any image in three phases.

• Removing background noise.
• Segmentation
• Matching the segmented part with alphabets.

Background noise removal is very easy for software, and is just achieved by some predefined formulas. Also, matching the segmented parts with alphabets and then predicting the alphabet is an easy task for the computer. The only task in which computer lag behinds us is segmentation. So, when writing a captcha by self, one should be careful enough to generate a captcha in which segmentation becomes difficult.

In the earlier time, captcha consisted of only distorted alphabets. However, now days it is very easy to crack them. So, a better captcha can be achieved by having couple of angled lines which will be overlapping characters, making it difficult for computer to automatically segment character. Another good technique can be clubbing the character so near to each other that they are almost overlapping or tilting alphabets in such a way that if divided horizontally, upper part of one alphabet will coincide with lower part of other.

These kinds of techniques will make sure that your captcha is really serving the purpose of captcha.