Image CAPTCHA based on distorted faces

An image recognition-based CAPTCHA is proposed for increasing security in web applications. The proposed method uses distorted faces to create an image for a CAPTCHA test. The user has to recognise the well-known person that appears in the image choosing the name from a list. The method uses a feature-line morphing technique to distort the faces which morphs the well-known person's face into a cartoon or an animal. The performance of this approach is evaluated through different face recognition systems. The results show an improvement in human recognition in comparison with word-based CAPTCHAs and an increment in robustness against robots when trying to break through the tests.