Practice Flashcards
Flip to reveal answersWhat is compression?
Track your progress — Sign up free to save your progress and get smart review reminders based on spaced repetition.
All 5 Flashcards — Compression
Sign up free to track progress and get spaced-repetition review schedules.
Question
What is compression?
Answer
Storing the same data in fewer bits. It works because real files repeat themselves, and smaller files need less storage and travel faster over a network.
Question
What is the difference between lossy and lossless compression?
Answer
Lossless can rebuild the original exactly — nothing is discarded, only written more briefly. Lossy permanently removes detail people are unlikely to notice, saving far more space but irreversibly.
Question
Explain run-length encoding with an example.
Answer
Each run of identical values is replaced by a count and the value. A row of six white pixels is stored as '6 white' — two values instead of six. Expanding it restores every original pixel.
Question
When does run-length encoding make a file bigger?
Answer
When neighbouring values rarely repeat, such as a detailed photograph. Most runs are length one, so storing a count beside every value adds data rather than saving it.
Question
Which method suits text, and which suits photographs?
Answer
Text, code and spreadsheets need lossless — one altered character can change the meaning. Photographs, music and video use lossy, because small losses go unnoticed and the saving is much greater.
Read the notes
Full study notes for Compression
Topic 1.1 hub
Hardware and operation
More from Topic 1.1
All flashcards in this topic
Computer Science exam skills
Paper structures & tips
Track your progress with spaced repetition
Sign up free — Aimnova tells you exactly which cards to review and when, so you remember everything before your IB exam.
Start Free