关键词: 滴水算法, 验证码, 粘连字符, 分割, 竖直投影

Abstract: Many researches demonstrate that good result can be gained by existing machine learning algorithms in the recognization of CAPTCHA（Completely Automated Public Turing test to tell Computers and Humans Apart） if single characters can be split. A method is presented to segment the merged characters in the recognization of CAPTCHA with touching characters. It seeks division points by combining the statistics of character width and the vertical histogram projection minimums, and then uses these points as the starting points of the drop fall algorithm to segment merged characters in CAPTCHA. The experiments show that it is a general method and can improve the recognization rate.

Key words: drop fall algorithm, CAPTCHA, merged characters, segmentation, vertical histogram projection