Quick comparison
| Feature | Lossy | Lossless |
|---|---|---|
| Data loss | Yes — some data permanently removed | No — original data fully recoverable |
| File size | Much smaller (5–50× reduction) | Moderately smaller (1.5–3× reduction) |
| Quality | Slight degradation (often invisible) | Identical to original |
| Formats | JPEG, WebP lossy, AVIF lossy | PNG, WebP lossless, TIFF, GIF |
| Best for | Photos, web images, documents | Logos, text, screenshots, medical images |
When to use lossy compression
Lossy compression is ideal when:
- You need to hit a specific file size target (e.g., 200KB for UPSC).
- The image is a photograph with gradual colour transitions.
- You're optimising for web performance (website speed guide).
- The slight quality loss is imperceptible to the viewer.
When to use lossless compression
Lossless compression is better when:
- The image contains text, logos, or sharp edges.
- You need to edit the image multiple times without degradation.
- Pixel-perfect accuracy is required (medical imaging, design assets).
- The image is a screenshot or diagram.
The hybrid approach: WebP and AVIF
Modern formats like WebP and AVIF support both lossy and lossless modes. WebP lossy offers 25–35% better compression than JPEG at equivalent quality. AVIF goes even further with 50% better compression. Use PhotoResizer.in's format converter to easily convert between formats.