| Aspect | Lossless | Lossy |
|---|---|---|
| Data Loss | None - perfect reconstruction | Permanent - some data removed |
| Compression Ratio | 30-70% smaller (moderate) | 80-95% smaller (extreme) |
| Reversible | Yes - decompress to exact original | No - cannot recover lost data |
| Best For | Text, programs, medical images, legal docs | Photos, music, video, web images |
| Examples | PNG, ZIP, FLAC, GIF | JPEG, MP3, MP4, AAC |
| When to Use | When every bit matters / exact copy needed | When human perception is primary concern |
This comparison covers Lossless vs Lossy Compression within Compression for GCSE Computer Science. Revise Compression in 3.3 Data Representation for GCSE Computer Science with 16 exam-style questions and 16 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 8 of 12 in this topic. Use this comparison to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Compression
Which statement correctly describes lossy compression?
Explain how run-length encoding (RLE) works to compress data.