Compression, Encryption & Hashing (OCR A-Level Computer Science): Flashcards
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Practise the cards
15 cards from this deck
Compression
Compression
Reducing the size of a data file
Two main types of compression
Two main types of compression
Lossy and lossless
Lossy compression definition
Lossy compression definition
Reduces file size by permanently removing some data
Is lossy compression reversible?
Is lossy compression reversible?
No - irreversible (data cannot be restored)
Lossy compression format examples
Lossy compression format examples
JPEG (images), MP3 (audio), MP4 (video)
Lossy compression main benefit
Lossy compression main benefit
High compression ratios/significant file size reduction
Lossy compression main drawback
Lossy compression main drawback
Quality loss - data permanently removed
Lossless compression definition
Lossless compression definition
Reduces file size without losing any data
Lossless compression reversibility
Lossless compression reversibility
Reversible - can decompress to exact original state
Lossless compression format examples
Lossless compression format examples
PNG (images), FLAC (audio), ZIP (files)
Lossless compression main drawback
Lossless compression main drawback
Lower compression ratios/larger file sizes than lossy
Best compression for web images
Best compression for web images
Lossy (e.g., JPEG) for faster loading times
Best compression for text documents
Best compression for text documents
Lossless (e.g., ZIP) - exact data retention needed
Best compression for medical images
Best compression for medical images
Lossless (e.g., PNG) - every detail critical
Best compression for streaming media
Best compression for streaming media
Lossy (MP3/MP4) - small files for efficient streaming