说明：   自从发表了用于验证码图片识别的类（C#代码）后，不断有网友下载这个类后，问如何用于一些特定的验证码。总结一下网友们的提问，很多都是不会从复杂背景中提到干净的字符图片来，这主要就是一个去噪问题，即除去图片上的背景、干扰点、干扰线等信息。
(Since the publication of the Verification Code for the type of picture identification (C# Code), the continuing users to download this category, the question of how for some specific Verification Code. Sum up the question raised by netizens, many of them are not from the complex background of the characters mentioned in a clean picture, this is a de-noising the main issues, namely, removing picture background interference, the interference lines of information.)