IGCSE Chapter 1.3.3 - Input Devices

Question 1

Types of Scanners

Answer 1

2D Scanners
3D scanners
Barcode Scanners/readers

Question 2

2D scanner

Answer 2

Most common form of scanners
generally used to input hard-copy paper documents
image is converted into electric form which can be stored in computer

Question 3

Stages of scanning using 2D scanner (7 steps)

Answer 3

1) cover raised, document placed on glass panel, cover closed
2) bright white light illuminates document, modern scanners usually use type of xenon lamp
3) scan head moves across document until whole page scanned
4) image of document produced and sent to a lens using series of mirrors, lens focuses image
5) focused image falls onto charge couple device (CCD) integrated circuits etched into silicon
6) CCD made of 1000s of light sensitive elements or pixels, each element creates electric charge when light falls on it
7) scanned image now turned into electric form, software produces digital image from electric form

Question 4

what software allows the scanned image to be turned into text file format

Answer 4

OCR optical character recognition software, scanned image can now be edited and manipulated by importing into word processor

Question 5

what format is original 2D scanned image

Answer 5

JPEG or another image file format

Question 6

3D Scanner

Answer 6

scan solid objects and produce 3D image
solid objects have x,y,z coordinates
scanner takes several points along these coordinates
digital image which represents object is formed
scanned image can be used in computer aided design, CAD, printed through 3D printer producing working model of scanned image

Question 7

technologies used in 3D scanner

Answer 7

lasers
magnetic resonance
white light

Question 8

application of 2D scanner at airport

Answer 8

used to read passports
use OCR technology to produce image of passport page
due to OCR tech digital images can be manipulated
OCR can review image, select text part and automatically put it into existing database
image of passport stored as jpeg
passenger face photographed and compared to digital image of passport photo
face recognition/detection software compares these two images

Question 9

positions of face which face recognition/ detection software uses

Answer 9

distance between eyes
width of nose 
shape of cheek bones
length of jaw line
shape of eyebrows
these key position are compared to see whether images belong to same face

Question 10

application of 3D scanning - computed tomography CT scanner

Answer 10

used to create image of 3D object
based on tomography technology
builds up an image of object through series of very thin slices
each slice built by use of X ray, radio frequencies, or gamma imaging
each slice stored as digital image in computer memory
whole of solid object represented digitally in computer memory

Question 11

Types of tomographic scanner based on which technology is used

Answer 11

X ray - CT scanners - computerised tomography
gamma ray - SPECT - single photon emission computed tomography
radio frequency - MRI - magnetic resonance imaging

Question 12

barcode

Answer 12

series of dark and light parallel lines of varying thickness

The numbers 0 to 9 are each represented by a unique series of lines

Question 13

UPC

Answer 13

Universal Product Code

Question 14

Universal Product Code

Answer 14

adopts different codes for digits appearing on the left and for digits appearing on the right

Question 15

actual left-hand and right-hand sides of the barcode are separated using

Answer 15

guard bars (two thin lines)

Question 16

each digit in a barcode is represented by how many bars

Answer 16

7 thin bars coloured black and white

Question 17

what is the relationship between same number code for barcodes but on different sides

Answer 17

they are the inverses of each other, anything coloured black on left side for same number will be white on right side

Question 18

special feature of barcode

Answer 18

can be scanned in any direction

Question 19

what happens when a barcode is scanned

Answer 19

• barcode read by red laser or red LED (light emitting diode)
• light reflected off barcode
• dark areas reflect little light or no light, white areas reflect more light which allows bars to be read
• reflected light read by sensors photoelectric cells
• as LED light scanned across barcode, pattern generated and converted to digital data
• this allows computer to understand barcode

Question 20

where are barcode readers most frequently found

Answer 20

at the checkout at supermarket

Question 21

what happens after barcode is read

Answer 21

• barcode number looked up in database, barcode is known as the key field in stock item record
• key field uniquely identifies each stock item
• when barcode number found stock item record looked up
• price and other stock item details sent to checkout or point of sale terminal POS
• number of stock items in record reduced by one each time barcode is read
• new value for number of stock items is written back to the stock item record
• number of stock items is compared to the re-order level; if less than or equal to value, more stock items are automatically ordered.
• Once an order for more stock items is generated, a flag is added to the record to stop re-ordering every time the stock item barcode is read.
• When new stock items arrive, the stock levels are updated in the database.

Question 22

Advantages of using barcodes to the management include

Answer 22

• much easier and faster to change prices on stock items
• much better, more up-to-date sales information/sales trends
• no need to price every stock item on the shelves (this reduces time and cost
to the management)
• allows for automatic stock control
• possible to check customer buying habits more easily by linking barcodes to, for example, customer loyalty cards.

Question 23

Advantages of using barcodes to the customers include

Answer 23

• faster checkout queues (staff don’t need to remember/look up prices of items)
• errors in charging customers are reduced
• the customer is given an itemised bill
• cost savings can be passed on to the customer
• better track of ‘sell by dates’ so food should be fresher.

Question 24

barcodes can be used in other areas such as

Answer 24

• library: borrowing books, borrower’s library card
• Every time a book is taken out, the borrower is linked to the book automatically. This allows automatic checking of when the book is due to be returned, for
  example.

Question 25

QR codes

Answer 25

Quick Response codes, another type of barcode

Question 26

Quick Response codes

Answer 26

made up of a matrix of filled-in dark squares on a light background