Text, Sound And Images
Overview
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.
Objectives
- 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 Understand how and why a computer represents sound, including the effects of the sample rate and sample resolution
- 3 Understand how and why a computer represents an image, including the effects of the resolution and colour depth
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Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Text, Sound And Images. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- How many different characters can a 7-bit ASCII code represent? A. 7 B. 64 C. 128 D. 256 Answer: C
- 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
- 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
- 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
- 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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