The bar code information can be defined by itself, and it is composed of several black lines with different thicknesses. Its most basic principle is "uniqueness" and it will not conflict or duplicate with the bar codes of other articles.

model number, size and color are all parts of barcode information, and model number, size and color are all variable here. The same model number and size can have different colors, bar code should be different, the same model number and the same color can have different colors, bar code should also be different, and so on.

Barcode identification method:

(1) The first three digits are country codes, such as 69~~693 for China; The next 4~5 digits represent the manufacturer identification code; The next 4~5 digits represent the product code; The thirteenth bit is the check code.

(2) calculation: add the last digit (except the check code, i.e. from the second right digit) to the second digit in front, multiply the single digit by 3, then add the single digit to the first digit, and then add it from the left to the right to the third last digit, and subtract the single digit of the number by ten to get the check code.

Recognition principle of bar code:

To convert a bar code compiled according to certain rules into meaningful information, it needs to go through two processes: scanning and decoding. The color of an object is determined by the type of its reflected light. White objects can reflect visible light of various wavelengths, while black objects absorb visible light of various wavelengths. Therefore, when the light emitted by the light source of the barcode scanner is reflected on the barcode, the reflected light shines on the photoelectric converter inside barcode scanner, and the photoelectric converter converts it into corresponding electrical signals according to the reflected light signals with different intensities. According to the difference of principle, scanners can be divided into three types: light pen, CCD and laser. The electric signal is output to the amplification circuit of barcode scanner to enhance the signal, and then sent to the shaping circuit to convert the analog signal into a digital signal. The widths of white bars and black bars are different, and the duration of corresponding electrical signals is also different. Then the decoder determines the number of bars and spaces by measuring the number of pulse digital electrical signals and 1. By measuring the duration of ,1 signal, the width of bar and space can be judged. At this time, the data obtained is still chaotic. To know the information contained in the bar code, it is necessary to change the bar symbol into the corresponding number and character information according to the corresponding coding rules (such as EAN-8 code). Finally, the detailed information of the article is identified by the computer system for data processing and management.