Data Storage And Compression
Overview
Every photo you take, every song you stream and every video you upload is, underneath, a long string of bits that has to be measured, stored and moved around. Knowing how to work out the exact size of an image or a sound file, and how compression shrinks that file without ruining it, turns a vague sense of 'big file, slow upload' into a precise, examinable skill.
In this lesson you will measure data in bits, bytes and the binary multiples up to the tebibyte, then calculate the size of an image file and a sound file from first principles. After that you will see exactly why files need compressing and how lossy and lossless methods, including run length encoding, achieve the saving.
Objectives
- 1 Understand how data storage is measured
- 2 Calculate the file size of an image file and a sound file, using information given
- 3 Understand the purpose of and need for data compression
- 4 Understand how files are compressed using lossy and lossless compression methods
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Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Data Storage And Compression. 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 bits are there in a byte? A. 2 B. 4 C. 8 D. 16 Answer: C
- An image is 200 x 100 pixels with a colour depth of 8 bits. Its size in bits is: A. 20 000 B. 160 000 C. 2 000 000 D. 1 600 Answer: B
- How many bytes are there in 1 kibibyte (KiB)? A. 8 B. 100 C. 1000 D. 1024 Answer: D
- Which statement about lossy compression is correct? A. It removes data permanently B. The original can always be rebuilt exactly C. It is ideal for text files D. It never reduces image quality Answer: A
- Run length encoding is best described as: A. a lossy method that deletes colours B. a lossless method that stores runs of repeating data as a value and a count C. a method only used on sound files D. a way of increasing file size Answer: B
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