Year 9 - Computing
File size and compression
Data representation: images and sound
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
In this unit, pupils will focus on digital media such as images and sounds, and discover the binary digits that lie beneath these types of media. They will explore how images and sound can be manipulated and consider the link between quality of images and sound and the resulting file size.
Lesson Summary
You will learn to explore what compression is and the impact it can have on the size and quality of a file.
Key Notes
- Compression is used to reduce the size of digital files.
- Lossy and lossless compression affects digital files.
- Using compressed files has both benefits and drawbacks for the use and transfer of file.
Vocabulary To Learn
- lossy compression: a method where data is permanently lost during the compression process and must be approximated when the file is decompressed
- lossless compression: a method of compression where no data is permanently lost during the process
Common Mistakes To Avoid
- Compression always reduces quality or that compressed files are always lower quality than uncompressed files.
3 Quick Questions (With Answers)
1. Describe the system or process from this lesson in clear steps.
Compression is used to reduce the size of digital files. Lossy and lossless compression affects digital files.
2. Define this computing term and give one practical example. 'lossy compression'
a method where data is permanently lost during the compression process and must be approximated when the file is decompressed. Add one real device or system example to prove understanding.
3. Correct this common computing misconception.
Mistake: Compression always reduces quality or that compressed files are always lower quality than uncompressed files. Correction: Lossless compression retains all original data by finding and storing repeated patterns more efficiently.
More Lessons In This Unit
Browse all guides in the Year 9 Computing guide library.