A new image-based CAPTCHA using the orientation of the polygonally cropped sub-images

Jong Woo Kim, Woo-Keun Chung, Hwan-Gue Cho. A new image-based CAPTCHA using the orientation of the polygonally cropped sub-images. The Visual Computer, 26(6-8):1135-1143, 2010. [doi]

Abstract

Abstract is missing.