Captcha Recognition

Captcha is computer generating text images used to distinguish interactions given by humans or machines. Normally, a captcha image consists of a fixed number of characters (e.g. These characters are not only distorted, scaled into multiple different sizes but also can be overlapped and crossed by multiple random lines. Two types of captcha illustrated in Figure 1, are specified by the number of character categories (0..9, A..Z) and the text length (e.g. 5 in green and 6 in black images). In this blog, I present and compare two deep learning models solving this captcha recognition challenge.