Basic Parameters of Scanner

Working Principle of Scanner: Currently, the working principle of desktop scanner is divided into two types: CCD and CIS. CIS products work like fax machines. They have no lens components, and use light emitting diodes as light sources and diode photosensitive elements. Because of its simple and compact structure, the volume can be made very small. The thickness of CIS products is usually less than half that of CCD products. However, CIS devices have no lens imaging part, so the depth of field is very small, and generally only planar objects can be scanned. Compared with CCD, CIS scanning technology uses optical imaging devices to scan images with very uniform color and brightness. In addition, using high-brightness light sources allows it to achieve very high color resolution. CIS technology uses large-area photosensitive devices, and it is difficult to ensure the uniformity of scanning at present. Moreover, CIS is not as good in color resolution as CCD because it uses diode light-emitting devices with lower brightness.

Largest aspect: Largest aspect refers to the scanner's maximum scanning size range, which depends on the scanner's internal mechanism design and the scanner's external physical size.

Take a flatbed scanner as an example (the scanning width is not much different from the overall size of the scanner). A4 size is the most common type, and the original input size of scanned manuscript can be A4(21cm×29.7cm) size at most. Of course, the size of the scanning area can be set by itself in the scanning range text box (enter the size number directly or adjust with the mouse).

Optical Resolution: The resolution of the scanner is the optical resolution, which refers to how many points are divided into on an inch, while the resolution of a 300dpi scanner means that it scans 300 optical points on an inch.

The scanner also has a maximum resolution, which mainly refers to the software interpolation on the optical resolution, that is to say, it is obtained through software calculation. Due to the difference of software algorithms, each scanning proposal may have very big difference. Generally, there are 9600dpi and 19200dpi. This indicator has little relation to the performance of scanning proposal.

Color depth: Color depth is also called color bits, which refers to the number of data bits that the scanner samples the image, that is, the color range that the scanner can discriminate. At present, there are 18, 24, 30, 36, 42 and 48 bits. It should be said that the higher the number of color bits, the more the scanner has the potential to improve the reproducibility of scanning effect.

Scanning speed: Scanning speed is an important indicator of the scanner. The so-called scanning speed generally refers to the time when the optical head moves from the beginning of preview to the completion of image scanning.

Scanning speed can be divided into pre-scanning speed and scanning speed. For these two speeds, we should tend to focus on the pre-scan speed rather than the actual scan speed. This is because the scanner is affected by the bandwidth of the interface (currently most scanners are USB interfaces) and the speed difference is usually not very large. However, the scanner must determine the position of the manuscript on the scanning platform through the pre-scanning step when starting to scan the manuscript, so the pre-scanning speed will greatly affect the actual scanning efficiency. Therefore, when selecting scanners, products with fast pre-scanning speed should be selected as far as possible.

Interface: Interface refers to the connection mode between scanner and computer. Interface technology is the most important technology of scanner besides imaging technology.
One of the techniques is directly related to the working efficiency of the scanner as an input device.

Scanning media: The scanning media is the type of media that the scanner can scan. The media that the scanner can process in general are photos, printed matter, manuscripts, positive and negative negatives, physical objects, etc.

Light source: The light source refers to the lamp tube inside the scanner body, which is self-contained with the stepping motor and moves together with the stepping motor. For the scanner, the light source is very important, because all the light felt on the CCD comes from the scanner's own lamp tube. The impure or partial color of the light source will directly affect the scanning results.

Transmission adapter: Transmission adapter is also called transparent scanning adapter, mask or transparent scanning wizard. Transmission adapter for flatbed scanner can allow users to scan negative films, slides and large transparent films or films.