Jul 13, 2015

Basic Knowledge of document scanners

Basic Knowledge of document scanners
1. The scanner is a high-tech electromagnetically integrated product. It is an important tool for transmitting the various forms of image information into the computer. It is the third generation of computer input devices after keyboard and mouse. It is a highly functional input device. People often use scanner for inputting computer image,from the direct images, photographs, graphics and film to all kinds of drawings of various types of document data using the document scanner, then it realizes computer processing of these images in the form of information , management, use, storage, output. Currently the portable scanner is widely used in image processing, publishing, and many areas of printing, advertising, office automation, multimedia, graphic database,graphic communications, engineering drawings,office supplies and other areas.

2. The document scanner’s composition? How does it work?
Document scanners are composed mainly of optical imaging  section, mechanical transmission parts and conversion circuit section. These parts cooperating with each other to reflect the characteristics of the optical image signals into electrical signals acceptable computer. Core part of the portable scanner is the photoelectric conversion unit complete photoelectric conversion. Currently most scanners photoelectric conversion unit uses what is called a charge-coupled device (CCD). It can be illuminated on the optical signal is converted into a corresponding electrical signal. The other main part of the composition has: a light source optical imaging part, an optical path and lens; conversion circuit portion A / D conversion processing circuit and the control circuit controls the mechanical part and the mechanical motion of the actuator stepper motor, and the scanning head and the rail. Reflected light  First, according to the light generated by the light source when the  document scanner is working on the artwork, it inputs an image characteristic or transmitted light (transmission version). Optical system gathers these rays to focus it on the CCD, the CCD optical signals then transmit into electrical signals, and then by the circuit part of these signals A / D conversion and processing to produce a corresponding digital signal to the computer.
3. How to classify the document scanner,.portable scanners and other scanners;Currently there are many types of scanners in the market, according to different criteria it  can be divided into different types. According to the  scanner principle,it  can be divided into  flatbed scanners, handheld scanners and photo multiplier tubes core of the drum scanners. And according to the  scanning image frame size,it  can be divided into small-format handheld scanners, desktop scanners medium-format and large-format drawings scanner, press scan artwork can be divided into a reflective media (paper) scanners and trans missive (film) scanners, it’s  Reflective transparencies can be a  versatile scanner.From the usage of the scanner it can be divided into general-purpose scanners,which can be used for all kinds of artwork  and dedicated scanner designed for the special image input devices such as bar code reading, card reading machines.
Key performance indicators of the best scanners
Scanner performance indicators are mainly represented by the  scanner accuracy resolution; represents a scanned image gray-scale gradation range; a scanning image color range of the number of colors, and the scan speed and scan format and so on. Resolution scanner surface indicates the ability to image detail, usually pixels per inch scanned image contained in the number, he said denoted DPI (Dot Per Inch). Currently, the majority resolution of the scanner between 300DPI-2400DPI. Gray level indicates the brightness level range of grayscale images. Series luminescence range more of the scanned image, the more rich layers. At present, most of the scanner is 256 gray. Number of colors represent the color range of the color scanner can produce. Usually indicates the color of each pixel data bits (bit) representation. For example, often said that the true color image refers to the color of each pixel with 24 binary number can represent a total of 224 = 16.8M colors, usually call this scanner as 24bit true color scanner. The more the number of colors to scan the image more vivid reality. There are several representations scanning speed, usually expressed in the resolution and image size specified scan time. Scan format scanning artwork represents the maximum size, a common A4, A3, A0 format scanners and so on for the office supplies.

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