Computer Science - 0478 CIE

Text, Sound And Images

Akopọ

Everything a computer stores, every essay, song and photograph, is held as nothing but ones and zeros. So how does a string of bits become the letter A, a drum beat, or a sunset? The answer is a set of clever, fixed rules for turning each kind of media into binary, and back again.

In this lesson you will see exactly how character sets like ASCII and Unicode encode text, how sampling captures sound, and how a grid of pixels stores an image. You will also learn the two dials, sample rate and resolution for sound, resolution and colour depth for images, that trade quality against file size, and you will calculate those file sizes yourself.

Awọn Afojusun

  1. 1 Understand how and why a computer represents text and the use of character sets, including American standard code for information interchange (ASCII) and Unicode
  2. 2 Understand how and why a computer represents sound, including the effects of the sample rate and sample resolution
  3. 3 Understand how and why a computer represents an image, including the effects of the resolution and colour depth

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Akọ̀wé Ẹ̀kọ́

A computer can only store and process binary, so before any text, sound or image can be saved, it must be turned into a pattern of bits. Understanding the rules behind that conversion lets you explain why a high quality photo is a large file, why a sound clip recorded at a higher rate sounds better, and why ASCII cannot cope with every world language. These ideas appear in almost every Data representation question.

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Ìdánwò Ẹ̀kọ́

Oriire fun ipari ẹkọ lori Text, Sound And Images. Ni bayi ti o ti ṣawari naa awọn imọran bọtini ati awọn imọran, o to akoko lati fi imọ rẹ si idanwo. Ẹka yii nfunni ni ọpọlọpọ awọn adaṣe awọn ibeere ti a ṣe lati fun oye rẹ lokun ati ṣe iranlọwọ fun ọ lati ṣe iwọn oye ohun elo naa.

Iwọ yoo pade adalu awọn iru ibeere, pẹlu awọn ibeere olumulo pupọ, awọn ibeere idahun kukuru, ati awọn ibeere iwe kikọ. Gbogbo ibeere kọọkan ni a ṣe pẹlu iṣaro lati ṣe ayẹwo awọn ẹya oriṣiriṣi ti imọ rẹ ati awọn ogbon ironu pataki.

Lo ise abala yii gege bi anfaani lati mu oye re lori koko-ọrọ naa lagbara ati lati ṣe idanimọ eyikeyi agbegbe ti o le nilo afikun ikẹkọ. Maṣe jẹ ki awọn italaya eyikeyi ti o ba pade da ọ lójú; dipo, wo wọn gẹgẹ bi awọn anfaani fun idagbasoke ati ilọsiwaju.

  1. How many different characters can a 7-bit ASCII code represent? A. 7 B. 64 C. 128 D. 256 Answer: C
  2. Which change increases the quality of a sound recording? A. lowering the sample rate B. increasing the sample resolution C. reducing the colour depth D. removing metadata Answer: B
  3. An image is 200 by 100 pixels with a colour depth of 8 bits. Its size in bits is: A. 2000 B. 20000 C. 160000 D. 1280000 Answer: C
  4. Why was Unicode created? A. to make files smaller B. to represent characters from many world languages C. to replace binary D. to remove the need for a character set Answer: B
  5. What does the colour depth of an image describe? A. the number of pixels in the image B. the width of the image C. the number of bits used per pixel D. the file format Answer: C

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Awọn Iwe Itọsọna Ti a Gba Nimọran

Cambridge IGCSE and O Level Computer Science Coursebook
Cambridge IGCSE and O Level Computer Science Coursebook
Atunkọ: Second edition
Olùtẹ̀jáde: Cambridge University Press
Odún: 2021
ISBN: 978-1-108-91514-4
Apejuwe: Endorsed coursebook with full coverage of the 0478/0984 syllabus, worked tasks and exam-style questions.
Cambridge IGCSE and O Level Computer Science
Cambridge IGCSE and O Level Computer Science
Atunkọ: Second edition
Olùtẹ̀jáde: Hodder Education
Odún: 2021
ISBN: 978-1-3983-1828-1
Apejuwe: Endorsed textbook covering the theory and the algorithms, programming and logic content.

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