An image scanner is an external computer device that captures images and converts them into digital input devices that the computer can display, edit, store, and output. It can extract and convert original lines, graphics, text, photos, and flat objects into digital forms that can be edited and added to files. In remote sensing applications, optical remote sensing images can be converted into digital remote sensing images and then input into a computer for processing.

Going to the computer market, it's not difficult for us to find over a dozen brands of scanners. Among the dazzling models, how do we choose? Generally, the following aspects can be considered:

1. Optical resolution DPI (i.e. scanning points per inch): Generally, it should reach 600x300 for household use, and not less than 600x600 for professional use;

2. The number of scanned digits: Most on the market are 30 or 32 bits, and professional ones choose 36 bits.

3. The size of the scanner: Generally, it is the size of A4 paper.

4. Scanner interface: Parallel interfaces are more economical, but the SCSI interface is not.

5. The provided software: The accompanying user software or drivers, as well as the user manual, are in Chinese.

The best-selling brands in the Chinese market include scanners from Microteck, HP, UMAX, AGFA, etc. You can choose according to your own needs and economic situation.