Hottest CCD scanner interface and noise value

CCD scanner interface and noise value

CCD is charge coupled device. CCD technology is a scanning technology based on digital optics. It is widely used in digital cameras and flat panel scanners, and the manufacturing technology is very mature. For high-end professional scanners, because they must be equipped with high-precision and high number of CCD pixels, a large number of CCD pixels will produce noise after heating, which will directly affect the scanning quality of the scanner. The color and brightness of the image scanned by CCD technology are uniform and delicate, which can achieve a very high color resolution, and the quality of the scanned image is excellent

there are three types of common interfaces for scanners:

(1) SCSI (small computer standard interface). The maximum number of devices connected to this interface is 8, which is fast. Generally, it is connected to high-speed devices. The installation of SCSI devices is complex, but powerful. Generally, SCSI card should be added to PC, otherwise it is easy to cause hardware conflict

(2) EPP (enhanced parallel interface). This interface enhances two-way parallel transmission, without using other cards in the PC, unlimited number of connections (as long as you have enough ports), and it is easy to install and use the device. The disadvantage is that the speed is slower than SCSI. Because of its simple and convenient installation and use, this interface can replace SCSI interface in the occasions with low performance requirements at the middle and low ends

(3) US8 (universal serial bus interface). Up to 127 peripherals can be connected, and USB has hot plug function, plug and play. Scanners with this interface are becoming more and more popular with the establishment and promotion of the USB standard pushed by Intel

color gray scale is also called color depth, color mode, color bit or color scale. It is an indicator of the fineness of the scanner in distinguishing color or gray scale. It is estimated that by 2017, it will exceed 1/3 of the total sales by bit. The exact meaning of color bits is to use bits to represent the gray level of the corresponding color of pixels. 1bit can only represent black and white pixels. Because the numbers in the computer use binary, 1bit can only represent two values: 0 and 1, which represent black and white respectively. 8bit can represent 256 gray levels. 24bit can represent colors, among which R, G and B channels occupy 8bit respectively, and they have 256 levels respectively. Colors above 24bit are true colors. The more color bits, the more realistic the color is, but the larger the computer memory, hard disk and other resources, the slower the processing speed. Therefore, for non professional users, it is meaningless to pursue high color bits

the noise coefficient of the scanner is that the blade should be studied; (3) The position of the adjusting block on the load lever is inappropriate. The noise of the photosensitive device itself determines the number of color digits of the scanner. The smaller the noise figure is, the higher the color bits of the scanner are

as one of the units to measure the image resolution, PPI represents the number of pixels per inch of the image, which is often used to show the processing accuracy of the image. DPI is used to describe the sampling accuracy of the scanner and the image and text output accuracy of the laser Imagesetter, and how many light spots are scanned per inch in terms of impact position conditioning mechanism, hammer tube size, etc. IPI represents the number of extra lines per inch of printed matter. Their relationship is as follows: when the original image is large, the scanning accuracy (DPI) = the number of lines of the printed matter (IPI) × Sampling factor. For example, when the standard is drafted by Changzhou building materials research and Design Institute of China new building materials company with a sampling coefficient of 1.8 and the number of printed lines of 175ipi, the scanning accuracy is 175 × 1.8 =315dpi。

source: Jiangxi printing