Why is the verification code of Baidu Post Bar difficult to distinguish?

). The verification code is generally to prevent batch registration, which is difficult for people to see, let alone the machine. Second, Baidu Post Bar does not log in or post. Probably to prevent the occurrence of large-scale anonymous replies. At present, many websites use verification code technology to prevent users from automatically registering, logging in and pouring water through robots. The so-called verification code is to generate a picture with a series of randomly generated numbers or symbols, and add some disturbing pixels to the picture (to prevent OCR). Users can identify the verification code information with naked eyes, enter the form and submit it to the website for verification. Only after the verification is successful can a function be used.

(2) General user ID registration places and major forums should enter verification codes.

(3). Universal verification code

1, four-digit, random one-digit string, the most original verification code, the verification effect is almost zero. 2.CSDN website users log in in GIF format, which is a commonly used random digital picture verification code. The characters in the picture are satisfied, and the verification effect is better than the last one. People without basic knowledge of graphics and iconography can't be broken! Unfortunately, on the first day of using CSDN, the program to read it seems to have been published on the forum. What a pity!

3.QQ website users log in in PNG format, and the pictures use random numbers and random capitalized English letters. The whole composition is a bit grandiose, and each character will change its position every time it is refreshed! Sometimes the photos taken can't be recognized by human eyes, which is amazing ... 4. When 4.MS applied for hotmail, it was in BMP format, with random numbers+random capitalized English letters+random interference pixels+random positions.

5. Google registered Gmail in JPG format, with random English letters+random colors+random positions+random lengths. 6. Other forums are in XBM format with random content.

(4) Significance: Many websites use verification code technology to prevent users from automatically registering, logging in and pouring water through robots. The so-called verification code is to generate a picture with a series of randomly generated numbers or symbols, and add some disturbing pixels to the picture (to prevent OCR). Users can identify the verification code information with naked eyes, enter the form and submit it to the website for verification. Only after the verification is successful can a function be used.