CAPTCHA Identification based on Image Denoising with PIL Filter
Tian Yong-xing · Computers & Security · 2012
CAPTCHA image is the major technique used by forums to tell computers and humans apart,SO that its security is of importance in internet usage.To learn about domestic CAPTCHA images,this paper proposes and implements a model of CAPTCHA image recognition algorithm,and tests almost all image types used in domestic forums.Experiment results indicate that a large part of CAPTCHA images have a recognition rate above 50%,and some with 100%,both of which Can hardly block automatic machines.In term s of its practicality,this paper further classifies them into four categories,only to find the optimal category is blank,which means CAPTCHA image technology needs great enhancements.