Year 10 - Computing
Compression ratios
Data compression
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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 be introduced to the concept of data compression and why it is needed. The will compare lossy and lossless compression methods and their typical uses. They will have the opportunity to compression methods such as run length encoding (RLE) and Huffman coding.
Lesson Summary
You will learn to describe and calculate compression ratios.
Key Notes
- The compression ratio is the ratio between the size of the original data and the size of the compressed data.
- A higher compression ratio usually reduces the file size more, but it can slow down performance or lower quality.
- When selecting compression algorithms data quality and processing speed must be considered.
- Higher compression ratios often require more processing power and time for both compression and decompression.
Vocabulary To Learn
- original size: the file size before any compression has been applied
- ratio: a comparison of the original file size to the compressed file size
- compressed size: the file size after compression has been applied
Common Mistakes To Avoid
- A higher compression ratio always means better quality.
3 Quick Questions (With Answers)
1. Describe the system or process from this lesson in clear steps.
The compression ratio is the ratio between the size of the original data and the size of the compressed data. A higher compression ratio usually reduces the file size more, but it can slow down performance or lower quality.
2. Define this computing term and give one practical example. 'original size'
the file size before any compression has been applied. Add one real device or system example to prove understanding.
3. Correct this common computing misconception.
Mistake: A higher compression ratio always means better quality. Correction: A higher compression ratio actually means the file size has been reduced more. This often results in lower quality, especially with lossy compression.
More Lessons In This Unit
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