Basic knowledge of the hottest scanner

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Scanner basic knowledge

now with the improvement of user level, it is no longer satisfied with simple computer host equipment, and there is an increasing demand for various computer peripherals, including printers, scanners, stylus, etc. As a product with a certain technical content, the scanner market continues to develop and the technology continues to progress

what is the use of scanner in daily study and work? A simple question: now the media is rich and colorful. We often see very good-looking posters, posters, graphic materials, which are very good. We want to collect them, but first of all, if they are borrowed, what should we do? Black out? NO! It's not a gentleman's act. Then, scan it into the computer with a scanner and save it. It can be accessed at any time, and it won't fade! There is a file that needs to be saved in the computer, but a comrade can't type or the speed is too slow, what can he do? With Scanner + scanning special recognition (OCR) software, it's easy to get it! You can taste coffee when others peck rice. See a picture of scenery, how beautiful!!! If you want to use it as a desktop background, you can simply do it with a scanner. You can enjoy it every day to obtain the best resonant frequency and hydraulic natural frequency required by the system

in short, the scanner can input media information such as printed copies, written manuscripts, photos, etc. into the computer, and then it can be compared with Beijing, Shanghai, Guangzhou and Shenzhen for processing at will through software to suit different applications. From a technical point of view, scanner is one of the devices that transform traditional analog images into digital images. It converts the analog optical signal of the original manuscript into a group of pixel information, and finally stores it in the digital file in a digital way to realize the digitization of the image

I. classification of scanners

(I) by interface mode

at present, the common interface modes of scanners (i.e. the connection mode between scanners and computers) include SCSI, EPP and USB:

1, SCSI interface. The scanner with SCSI interface needs a SCSI card to connect the scanner with the computer (the required SCSI card is usually included in the scanner). Most of the early scanners were SCSI interfaces. The advantages are fast transmission speed and high scanning quality; The disadvantage is that you need to open the chassis and install a SCSI card, which will occupy an ISA or PCI slot and the corresponding interrupts. The installation is relatively complex and may conflict with other accessories

2. EPP interface. It is what we often call a print port (parallel port). Compared with SCSI scanners, the speed is slow and the scanning quality is slightly poor, but it is easy to install and has good compatibility. Most scanners using EPP interface have two interfaces at the back, one connected to a computer and the other connected to other parallel port devices (usually printers)

3. USB interface. It is the latest interface form. Generally, ATX motherboards have their own USB interface, while old at motherboards generally do not (some newer at motherboards have USB connection ports, but you need to buy another connection cable). The advantage is that the speed is faster than EPP, and it can be plugged in and out, plug and play. The newer USB scanner can be powered directly from the USB port without additional power supply. The disadvantage is that the old model of machine can't be used, and the selling price is a little higher than that of EPP

from the above three points, it can be seen that industry and professional users or users who have strict requirements for effect can choose SCSI and USB scanners as much as possible, and EPP can be selected for general office use

(II) according to the working principle

from ancient times to the present, there are handheld, flat panel, special film, roller and CIS scanners

1. Handheld. It's almost invisible now. Long ago, it was used because it was cheap. The optical resolution is generally between 100dpi and 600dpi, mostly black and white. Wet molding

2, flat type. Also known as CCD scanner, it mainly scans reflection documents. The optical resolution is 300dpi-2400dpi, and the number of color bits has reached 48

3. Film scanner. It is mainly used to scan slides, photographic negatives, CT films and professional films, with high precision and strong sense of hierarchy, and the attached software is more professional

4. Roller type. The scanner samples pixel by pixel with a point light source, and uses RGB color separation technology. Of course, the advantages are obvious. It is truly professional, and the price is also professional

5. CIS scanner. It is a new scanner that came out only after 98 years. CIS means contact image sensor, which does not need optical imaging system. It has simple structure, low cost, light and practical. However, it has strict requirements on the thickness and flatness of the scanned manuscript, and the imaging effect is worse than that of CCD

of course, now there is a CCD scanner with TMA (transmission scanner), which can scan film

second, the technical indicators of the scanner

when we contact the scanner, we will see a variety of technical indicators. Here is a brief introduction to the common indicators

1. Scanning accuracy. Resolution, as we often call it, is an important parameter to measure the level of a scanner. It reflects the degree of precision that the scanner can achieve when scanning. The scanning accuracy is usually expressed in dpi (resolution), which is similar to the technical indicators of inkjet printers. The higher the DPI value, the finer the image scanned by the scanner. Scanning resolution is divided into optical resolution (real resolution) and interpolation resolution (maximum resolution). The former is in the form of hardware and the latter is in the form of software

2, color digits. The number of color bits indicates the scanner's ability to recognize colors and the color range it can describe. It determines the authenticity of color restoration. The larger the number of color bits, the better and more realistic the scanning effect is, and the less distortion in the scanning process

3, gray level. The gray level of the scanner reflects the ability to provide a range of levels from dark to light during scanning, specifically, the ability of the scanner to smoothly transition from pure black to pure white. The larger the number of gray level digits, the richer the level of scanning results and the better the effect

4. Scanning format. Refers to the range that the scanner can scan, that is, the size of the paper, generally A4, a4+, A3, etc

5. Compatibility. Almost all scanners can be used for PC, and many SCSI and USB scanners are marked as MAC compatible (Apple)

6. System environment. Scanners need drivers to work. Under which systems can these drivers be used, such as Win98, WIN2000, WinNT, etc. in addition, some SCSI and USB scanners also have drivers for MAC (Apple) OS

7. Optional accessories. It usually refers to the paper feeder (ADF) and the thru scanning adapter (TMA). Not all scanners support additional accessories. As mentioned earlier, some scanners incorporate TMA

III. scanning software

1. Image. Scanning objects are used for image processing, such as Photoshop, self shape self element, scanning master, and windows' own imaging program

2. OCR. Scanned objects are used for word processing, and image files are converted into text files, such as Tsinghua Ziguang OCR, Shangshu OCR, Mengtian OCR, Wentong OCR, and textbridge for English recognition

3. Vectorization software. For professional drawing scanning, it usually needs to cooperate with engineering scanners (A0 or super A0 large format). Almost all scanners do not bring them, and they need to be purchased separately. Tsinghua unisplenum is common

IV. scanning principle

at present, scanners on the market use two completely different manufacturing principles. One is CCD technology, which uses the lens to image onto the photosensitive element; The other is cis contact scanning. CIS technology used to be mainly used in fax machine manufacturing. Its image will be directly recorded by CID photosensitive element after being scanned with LED lamp, without using lens refraction, so the whole body can be made very light and thin. It is more suitable for scanning documents or general plane graphics and texts, but not for scanning three-dimensional objects or transmissive manuscripts (Note: transmissive manuscripts are manuscripts that light can pass through, such as negatives, slides, etc.)

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