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Sample report: scanners

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Sample report
Computer systems computer systems
Topic: scanners
Abstract
This report investigates the current state of scanner technology and examines the
predicted future advancements of scanners. A brief history of the scanner and its
operation is initially outlined. The discussion then focuses on the advantages and
limitations of the five main types of scanners in common use today: drum, flatbed, sheet-
fed, slide, and hand held scanners. The performance of these scanners is examined in
relation to four main criteria: resolution, bit-depth, dynamic range and software. It is
concluded that further technological advances in these four areas as well as the
deployment of new sensor technology will continue to improve the quality of scanned
images. It is also suggested that specialised scanners will increasingly be incorporated
into other types of technology such as digital cameras.
Table of contents
Abstract i
1.0 Introduction 1
2.0 How scanners work 2
3.0 Types of scanners 2
3.1 Drum scanners 2
3.2 Flatbed scanners 2
3.3 Sheet-fed scanners 2
3.4 Slide scanners 3
3.5 Hand held scanners 3
4.0 Scanner specifications 3
4.1 Resolution 3
4.2 Bit-depth 4
4.3 Dynamic range 4
4.4 Software 4
5.0 Future developments 5
6.0 Conclusion 5
7.0 Reference list 5
Appendicies 6
Appendix 1 Image Sensor Scanner 8
Appendix 2 Frequently Used References 9
Appendix 2.1 Scanner Tips 10
Appendix 2.2 Scanners, Digital Cameras and Photo CDs 11
Appendix 2.3 The PC Technology Guide 12
1. Introduction

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The purpose of this report is to survey the current state of scanner technology and to
briefly discuss predicted advancements in the field.
By examining a range of recently published journal articles, magazine articles and
internet sites on the topic of scanners this report describes the main types of scanners in
common use today and examines their performance in relation to four criteria: resolution,
bit-depth, dynamic range and software. The report then considers the effect of further
technological advances in these four areas, as well as the deployment of new sensor
technology on the future development of scanners.
The first scanner, initially referred to as a 'reading machine', was developed in 1960 by
Jacob Rabinow, a Russian born engineer. The device could scan printed material and then
compare each character to a set of standards in a matrix using, for the first time, the "best
match principle" to determine the original message (Blatner, Fleishman and Roth 1998,
p.3). This reading machine was to form the basis for the development of current scanning,
sorting and processing machines.
An early improvement on the reading machine was the drum scanner. These scanners
used a type of scanning technology called photomultiplier tubes (PMT). Drum scanners
are still used in industry today because of the high quality images they produce. The
development of smaller, more economical scanners such as desktop scanners and
scanners for domestic use followed the drum scanner as the number of computer users
increased and computer technology advanced.
Scanners can now capture images from a wide variety of two and three dimensional
sources. These images are converted to digitised computer files that can be stored on a
hard-drive or floppy disk. With the aid of specific software, these images can then be
manipulated and enhanced by the user. It is now possible to deploy electronic acquisition
to create an entire layout (including all graphic elements) from the same computer. This
means manual stripping is no longer required (Scanners, digital cameras and photo CDs
2000). Scanners are considered an invaluable tool for adding graphics and text to
documents and have been readily adopted by both business and domestic users.
2. How scanners work
A scanner is a device that uses a light source to electronically convert an image into
binary data (0s and 1s). This binary data can then be used to store the scanned image on a
computer. A scanner recreates an image by using small electronic components referred to
as the scanner's 'eyes' (Scanner tips 2000). The type of 'eyes' used in today's scanners are
charge-coupled devices (CCD) and photomultiplier tubes (PMT). These electronic eyes
measure the amount of light reflected from individual points on the page and translate it
to digital signals that correspond to the brightness of each point (Englander 2000).
To create a file on the computer that represents a colour image, the scanner divides the
image into a grid with many individual points called pixels or picture elements (Scanner
tips 2000). A scanning head, termed a row of 'eyes', reads over the grid and assigns a

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number to each pixel based on the main colour in that pixel, using green, blue and red.
For example an aqua pixel would be saved as a number to represent the proportion of
blue, green and red which represents the colour aqua (Scanners, digital cameras and
photo CDs 2000).
3. Types of scanners
There are five main types of scanners in common use today: drum scanners, flatbed
scanners, sheet-fed scanners, slide scanners, and hand held scanners.
3.1 Drum scanners
Drum scanners were widely used in the past, however they are much less commonly used
today due to advances in scanner technology. As a result of their expense, these machines
are primarily used by professionals in industry, where they are considered important due
to the high-end quality image they produce and because they use PMT technology which
is more sophisticated than charge-coupled devices (CCDs) and contact image sensor's
(CISs). Drum scanners are difficult to operate and technicians operate these scanners by
placing the item to be scanned on a glass cylinder rotating at high speeds around the
sensor (Sullivan 1996).
3.2 Flatbed scanners
The most popular scanners for general use are flatbed scanners. This type of scanner is
highly versatile because it is able to scan flat objects as well as small three dimensional
objects. Flat-bed scanners operate by placing the item to be scanned on a glass window
while scanning heads move underneath it. A transparency adapter is used to scan
transparent originals such as slides or x-rays, and an automatic document feeder is
available for scanning large numbers of documents (Scanner tips 2000).
3.3 Sheet-fed scanners
Sheet-fed scanners have grown in popularity in recent years, particularly for small office
or domestic use as they are reasonably priced, can scan full-sized documents and are
compact, requiring limited desk space (Scanner tips 2000). Most models of sheet-fed
scanners have an inbuilt document feeder to overcome the problem of manually feeding
one sheet of paper at a time. However the actual process or scanning with a sheet-fed
scanner may result in distortion as the image to be scanned moves over the scanning
heads (Scanner tips 2000). A further limitation of sheet-fed scanners is that they are
unable to scan three dimensional objects.
3.4 Slide scanners
This type of scanner is used to scan items such as slides that need careful handling during
scanning. Unlike other scanners, the scanning heads in slide scanners do not reflect light
from the image, but rather pass light through it. This enables these scanners to produce
superior results without distortions caused by reflective light. To be able to scan small
and detailed items, these scanners have a large number of eyes on the scanning head
which produces a high quality result. Slide scanners tend to be more expensive and less
versatile than flatbed and sheet-fed scanners as they are limited to only scanning slides

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