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Scanners 101
Table of Contents 1. What is a scanner? 2. Different types of scanners. 3. All-in-one's. 4. Terms to know. 5. How scanners work. 6. Connection interfaces. 7. Sources
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1. What is a scanner?
![]() A scanner is a hardware used to import tangible media documents such as pictures or documents; it then converts this to a storable computer format so that the computer can understand. It does this by digitizing the image or document for colors, patterns, marks, and many other things; then stores theTop of pagem in a format the computer can understand; such as an image format, .bmp, .gif, .jpg, etc. Depending on the scanner and type, it could recognize documents with prints or letter characters and put the information in an editable document file that you can manipulate or edit. In similarity, it reads the patters and marks on a picture, reproducing it as close as possible and storing it as an image file. Certain scanners have the ability to scan objects too, which will be discuseed later on. Top of page
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2. Different types of scanners.
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"Remember, wrong advice may be worse than no advice at all." ::COMPUTERHAKK::: Last edited by DCIScouts; 10-26-2006 at 08:00 AM. |
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3. All-in-one's
Why isn't this with "Different types of scanners?" Well, you wouldn't really consider any of these scanners so they wouldn't really fit in that category. These units usually have many features such as a printing feature, faxing feature, scanning feature, copying feature, and many more. An All-in-one (AIO) is really just a printer with a scanning unit with added features. The benefits of these units are that they save you a lot of space considering if you were to get a scanner, printer, fax machine, and copy machine. Another added nifty feature is that AIO units will allow you to scan and print right there and then rather than taking additional steps on the computer. Top of page
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"Remember, wrong advice may be worse than no advice at all." ::COMPUTERHAKK::: Last edited by DCIScouts; 10-30-2006 at 05:38 AM. |
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4. Terms to know
Terms that you should really look into when purchasing a scanner for the first time. These terms and it's information should be what aids you in your choice of picking this scanner over that other one.
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"Remember, wrong advice may be worse than no advice at all." ::COMPUTERHAKK::: Last edited by DCIScouts; 10-26-2006 at 07:51 AM. |
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5. How scanners work
For the most part, pertaining to most scanners, except drum scanners. As unique as they are, for the most part they work in very similar ways. A media file (document or picture) is placed face-down on a glass sheet made available when you open up a hinged panel which protects the glass sheet. A scanning array consisting of a lamp, a mirror, a lens, and an image sensor is booted up and at this stage, may take a while for it to warm up. When it is complete, the scanning process starts. The sensor moves back and forth underneath the glass making sure that all areas are scanned and recorded, even the area that you don't want scanned. Now, depending on the scanner, the sensor could either be:
![]() Image courtesy TASI (Technical Advisory Service for Images), United Kingdom (tasi.ac.uk). Now, the CCD image sensor is a single row of sensor elements mounted on a moving platform which comes up very close to the media being scanned. Light from the lamp bounces off the original media above the glss sheet and is then reflected by mirrors on both sides into the lens. The lense then focuses the image into the CCD. Now, the CCD or CIS digitizes this information and converts it from analog-to-digital (ADC) then sends it to the scanner's internal workings. Lastly, the scanner sends this digitized format to the pc software, where you can view it as a readable computer format. So either CCD or CIS, they work similarly, but just read the data from the media differently. On flatbeds, you would usually find CCD sensors which moves to and about the glass sheet while on the sheetfed and those alike, you will find more of the CIS sensors which doesn't require the use of mirrors to bounce off the lights. For preference, the CCD usually perform better than a CIS sensor because everything is usually done within the sensor itself rather than have it bounced off lights. This, in-terms usually called for cheaper manufacturing and cheaper scanners; in all, cheaper quality and results that tend to be a little bit noisy as compared to CCD. That's why singlesheet, sheetfed, etc. type scanners are cheaper and produce poorer results. When scanning color, the scanner sensor usuall take several trips back and forth; each time changing the color of the lamp. Scanning black/white images were fairly easy as it didn't need different colored lamps to display different colors. However, when color scanning was introduced, new ways of scanning were developed. Instead of just having one shade of lamp, there were now about 3 different colored lamps; Blue, Red, and Green. Each time the sensor passes the media, a different lamp was illuminated and the data is sent back to the scanner to compile. When it was done, this compiled data was digitized and sent to the pc where you can now see it as a readable computer format. Eventually, people were getting impatient and couldn't stand the wait of having the scanner go back and forth 3-4 times and sometimes getting stuck along the way. So, a newer method was introduced. This time, light sensitive CCD/CIS sensors were produced where it was able to recognize the different Blue, Red, and Green hues, so it eliminated the wait time for those impatient owners. Drum scanners Working in a different way than what was just described above, drum scanners spins your media or object rather than scan it. The media is placed on a cylindrical drum (how it got it's name). A small path of light is shined on the media and when the drum spins, the light is moved a line of pixel at a time. Now, this whole process involves PMT (Photo Multiplier Tubes); PMT are used because they are more effective than CCD or CIS because they can pick up the darker/lighter/shadows more effectively and give you a much accurate read of the media. In the case of the CCD or CIS, they would just register this as dark or light, but not anything inbetween. Top of page
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6. Connection interfaces
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