Anti-cracking Technology for Captcha Recognition
Zhenjun Fan · 2018
This paper deals with the formation of the closely-related Captcha image styles. By the calculation of void spots (value of 0)in each character lattice of captcha image, the minimum distance between blank spots of adjacent characters lattice can be found. Then based on this minimum distance, operation such as transverse displacements, zooming, and twisting of characters can form the closely-related Captcha image styles. The image style can effectively prevent character segmentation and increase the machine recognition difficulty. This paper illustrates a realization of captcha on linux system based on C language. The image file, without any graphic library support, is less than 4k and the executable file size is 25k. This system is in its strong commonality. For example, it can be used in embedded system.