3.4 Input and output considerations CCDs are not inherently able to detect colour, only brightness. So it is necessary to rely on the fact that any colour of light can be made up from the three primary colours of light: red, blue and green. (Note that the three primary colours of light are different from the three primary colours of pigments.) Each CCD in the array is therefore overlaid with a red, blue or green filter and so detects the brightness of, respectively, the red light, the blue light or the green light falling on it
3.1 Introduction Digital cameras need to represent still pictures digitally,
2.2.3 Positive integers: converting denary numbers to binary If computers encode the denary numbers of the everyday world as binary numbers, then clearly there needs to be conversion from denary to binary and vice versa. You have just seen how to convert binary numbers to denary, because I did a couple of examples to show you how binary numbers ‘work’. But how can denary numbers be converted to binary? I'll show you by means of an example. 15 Computers and communication systems working together The combination of communication systems and computers has produced powerful new systems not possible when these technologies are used separately. In section 15–19, I'll be using an ICT system in a supermarket as an example, as it is something that you have probably experienced. The material in this study session is not intended to be a comprehensive examination of how ICT systems are used in supermarkets; I'll just be focusing on some of the supermarket's activities in order to highlight t 14.1 Introduction Now that I have introduced you to the processes carried out by a stand-alone computer, I will move on to discuss what happens when computers are linked. 10.2 Ports On the outside of a computer you will see a number of connection points that look like sockets. These sockets are known as ports and they provide connections between the computer and external devices such as a digital camera or printer. Ports control the flow of data between the computer and these devices, ensuring that data is sent and received quickly and reliably. Modern ICT devices require increasingly large amounts of data to be sent between the computer and the devices. The 3.2 Looking into the 'means of conveying a message' The diagram in Figure 6 shows that, for communication to take place, there needs to be some means of conveying the message between the sender and the recipient. I am now going to look at the essential components of ‘means of conveying a message’. In other words, I shall treat ‘m 2.3 Models of an ICT system To help me to introduce you to important ideas about ICT systems, I'm going to take a three-stage approach. ICTs involve conveying, manipulating and storing data. This is going to be the basis of my approach. Firstly, in the next few sections, we'll look at ICT systems where the primary function is to convey data. We can think of these systems as communication systems and I'll use a mobile phone system as an example. In sections 8–14, I'll focus on ICT systems wher 2.2.2 Drawing the boundary Deciding where to place the system boundary is an important consideration in that we have to think about what to include and exclude. This isn't always an easy decision to make and it often depends on the perspective of the person viewing the system. The system maps in Figures 1 5.1 Introduction The word usability has cropped up a few times already in this unit. In the context of biometric identification, usability referred to the smoothness of enrolment and other tasks associated with setting up an identification system. A system that produced few false matches during enrolment of applicants was described as usable. Another meaning of usability is related to the ease of use of an interface. Although this meaning of the term is often used in the context of computer inter References 1.3.4 How to use colour to good effect The effective use of colour is a complex and technical area. In Table 2 we have listed some general guidelines. 2.3 How to use text to good effect Two aspects of the use of text are: How to ensure that your text is legible. How to write text that suits the medium. We consider the first of these in this section. We do not cover how to write English that is appropriate for your particular readers here. However, it is important to ensure that your text does not contain words or expressions that may be unclear to your readers. You must select text that is meaningful 7 The PDCA cycle In Section 5 you were introduced to the nine-stage ISMS planning process advocated by the Standard. You have also, in Sections 5 and 6, looked in some detail at some of these stages – those comprising the ISMS documentation and asset identification tasks. However, an ISMS must not only be planned, it must also be implemented, operated, monitored, reviewed, maintained and improved. Part 2 of the Standard provides guidance on these processes, which it suggests should be undertaken follo Other approaches to information security management Many of the approaches to planning an ISMS to be found in the literature follow a three-phase, rather than a four-task, approach. For instance, Moses (1994) stipulates seven steps in three phases: initiation: the identification of information assets and their security requirements; analysis: the identification of possible risks to the security requirements of information assets, of the vulnerabilities to those risks, and 2.3 Trojans The term Trojan comes from the Greek legend about the fall of the city of Troy. The story goes that, during the seige of the city by the Greeks, a huge, hollow wooden horse was left in front of the gates. The inhabitants thought that it was a peace offering from the Greek army and dragged it into the city. Unknown to them, it was being used to conceal Greek soldiers, who were thus able to use this Trojan horse to enter the city and open the gates for the rest of their army. 2.1 What is a virus? A virus is a piece of computer code – a program – that has been written to gain access to files or programs on your computer. The virus may enter your computer via floppy disk, by email or by your Internet connection. It will look at the files on your computer and infect some of them if it can. Introduction
The World Wide Web is a vast information resource. This unit will provide you with the foundation skills to use search engines confidently to locate both information and images on the Web. You will also learn how to critically assess and reference the information you have found for study purposes. 6.9 The personalised home In the extract from The Road Ahead, quoted at the beginning of this section, Gates makes reference to ‘an electronic pin to clip to your clothes’. This pin appears to have the ability to communicate to the network so that its wearer can be identified and located. The information can then be used to provide a personal environment for the wearer. The next section introduces you to a technology that can provide the kind of pin that Gates refers to. 4.9 Bluetooth The driving force for the development of the Bluetooth standard was to eliminate the need for connecting wires between local ICT devices such as keyboards, monitors, printers, PDAs (Personal Digital Assistants), cell phones and headsets. This was already possible using infrared technology, but the requirement for line-of-sight positioning between the communicating interfaces limits infrared's usefulness. Because Bluetooth uses radio waves, Bluetooth devices can communicate with each other wit
Table 2: Making e
