Image scanner
A scanner is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. Common examples found in offices are variations of the desktop (or flatbed) scanner where the document is placed on a glass window for scanning. There are 3D scanners used for industrial design, reverse engineering, test and measurement, orthotics and other applications. Mechanically driven scanners that move the document are typically used for scanning large- -format documents, where a flatbed design would be impractical.
Modern scanners typically use a charge-coupled device (CCD) or a contact image sensor (CIS) as the image sensor, whereas older drum scanners use a photomultiplier tube as the image sensor. A rotary scanner, used for high-speed document scanning, is a type of drum scanner. Anther type of scanner is planetary scanner, which takes photographs of books and documents. 3D scanners are used for producing three-dimensional models of objects. Another category of scanner is digital camera scanner, which is based on the concept of a reprographic camera. Due to increasing resolution and new features such as anti-shake, digital cameras have become an attractive alternative to regular scanners. While still having disadvantages compared to traditional scanners (such as distortion, reflections, shadows, low contrast), digital cameras offer advantages such as speed, portability, digitising of thick documents without damaging the book spine. New scanning technologies are combining 3D scanners with digital cameras to create full-colour, photo-realistic 3D models of objects.
A flatbed scanner is usually composed of a glass pane, under which there is a bright light (often xenon or cold cathode fluorescent) which illuminates the pane and a moving optical array. CCD type scanners typically contain three rows (arrays) of sensors with red, green, and blue filters. The same light sensor system is used in digital cameras and camcorders.
A CCD is simply an array of light-sensitive diodes, which generate electrical signals in response to light photons. Each photodiode records a pixel, a tiny dot representing the light that hit that spot. Collectively, the light and dark pixels form an image of the scanned document (a photograph, for example). An analogue-to-digital converter in the scanner system processes the analogue electrical signal to generate a digital representation of this image.
CIS scanning consists of a moving set of red, green and blue LEDs strobed for illumination and a monochromatic photodiode array for light collection. Documents to be scanned are placed face down on the glass, an opaque cover is lowered over it to exclude ambient light, and the sensor array and light source move across the pane, reading the entire area. Only the light that an image reflects is visible to the detector. Transparent images do not work in this way, and require special accessories that illuminate them from the upper side. Many scanners offer this as an option.
Scanners typically read red-green-blue colour data from the array. This data is then processed with some proprietary algorithm to correct for different exposure conditions, and sent to a computer. Colour depth varies depending on the scanning array characteristics, but is usually at least 24 bits. High quality models have 48 bits or more colour depth. The other qualifying parameter for a scanner is its resolution, measured in pixels per inch (ppi). A good flatbed scanner has an optical resolution of 1,600 - 3,200 ppi. Instead of using the scanner's true optical resolution, the only meaningful parameter, manufacturers like to refer to the interpolated resolution, which is much higher thanks to software interpolation.
Scanning the document is only one part of the process. For the scanned image to be useful, it must be transferred from the scanner to an application running on the computer. The amount of data generated by a scanner can be very large - a 600 dpi A4 (210 x 297 mm) uncompressed 24-bit image is about 100 MB of data which must be transferred and stored.
Four standard connections are used by scanners for data transferring: parallel port, small Computer System Interface (SCSI), Universal Serial Bus (USB), and Fire Wire.
Ćwiczenia
I. Napisz poniższe zdania w trybie warunkowym:
1. The picture is too big for my scanner.
2. She has probably found a new job.
3. She probably found a new job last year.
4. Can you take care of the kids this afternoon?
5. Magda suggested I ought to take a day off.
6. She does not accept his proposal.
7. He doesn't study so hard.
8. Perhaps Peter was ill yesterday, (might)
II.Przetłumacz na język polski:
1. I brought my computer to the workshop to be repaired.
2. These techniques allow an incredible amount of information to be crammed into the 3,000 Hz of bandwidth.
3. To be introduced to the president you must have a recommendation of our foundation.
4. A modem is needed to be connected to the Internet.
5. It is quite possible for an email message to be read and even tampered by third parties.
6. These systems allow files to be shared in voice and video formats.
7. Sound flies may be played back on a computer or shifted to a digital audio player to be listened to on the move.
8. Internet is a common noun, a synonym for internetwork; therefore is not to be capitalised.
9. AT&T maintained a monopoly on the use of its phone lines, allowing only AT&T-supplied devices to be attached to its network.
10. The Internet became known as a service, similar to TV or radio, and the word came to be used in this way.
III. Wstaw angielski odpowiednik polskiego zwrotu:
11. (Coraz mniej ludzi) read books for pleasure.
12. Next month George will be going to Japan (po raz drugi).
13. I'm not quite sure, but I'm inclined to believe that Andrew is (albo elektronikiem, albo informatykiem).
14. Betty needs a good dictionary (dla siebie).
15. I have a lot of friends, but (żaden z nich) has a fax machine.
16. John is pleased with his job, because it offers him (perspektywy na lepszą przyszłość).
19. This time next Saturday Mr. Jackson will be (w drodze do Nowego Jorku).
20. They've been in London (od przedwczoraj).
IV.Przetłumacz na język angielski:
V.Wstaw odpowiedni czasownik złożony:
believe in, blew up, came across, go over, looking for, made up, set off, take back, take up, tell off, turn down
1. Let's the grammar one more time before the test.
2.I was an old computer magazine when I ……………… this photograph of my school class.
3. There is just too much work to be done. We'll have to ……………… some new employees.
4. You don't think I that ridiculous story you have ……………… , do you?
5.I think you need to a new hobby to help you relax.
6. When the father saw what had happened with his camera he ……………… and shouted at his son.
7. I had to her offer of a job at such small software company.
8. We at six in the morning on our drive to the coast.
9. I want you to every bad word you've said about my brother.
10. I had to ……………… Bob because of his poor performance recently.
elektrapsk