Topic Three (1.3): Representing Text, Images and Sound

In this topic, you will learn how computers convert input text, images and sound into binary in order to represent them on screen or through audio output devices.

For text, you will learn about the two main character sets used – ASCII and Unicode – and the differences between them.

For images, you will learn how binary is used to represent pixels and thus define the resolution of an image.

For sound, you will learn how sound is sampled by a computer to create sound waves. You will also learn about sample rates and sample resolutions.

Read Icon.png Read

Please read through and make notes on pages 21 to the top of page 25 in your coursebook and complete Activities 1.2 and 1.3.

Link Icon.png Links

Please work through the following resources.

A very nice, detailed explanation of ASCII and Unicode:

EXPLORE – Representation of Text (αda) Links to an external site.

While the coursebook focuses on pixel-based (or bitmap) images, this very useful page explains how binary can be used for both bitmap and vector images, as well as explaining the difference between them:

READ – How Can an Image be Represented in Binary? (Teach Computer Science) Links to an external site.

A nice clear explanation of how computers represent sound:

READ – Representing Sound (Isaac Computer Science) Links to an external site.