compression2025-01-20
Image Compression Principles Explained
Learn how image compression works and why it matters for web performance.
Image compression reduces file size while maintaining acceptable visual quality.
Types of Compression
Lossy Compression
- Permanently removes data
- Smaller file sizes
- Some quality loss
- Examples: JPEG, WebP
Lossless Compression
- No data is lost
- Larger than lossy
- Perfect quality
- Examples: PNG, GIF
How JPEG Compression Works
1. Convert RGB to YCbCr 2. Apply Discrete Cosine Transform 3. Quantization (data loss happens here) 4. Entropy encoding
Quality vs File Size
| Quality | File Size | Use Case | |---------|-----------|----------| | 90-100% | Large | Print, archive | | 70-85% | Medium | Web, general use | | 50-70% | Small | Thumbnails |
Best Practices
- Choose the right format for content
- Compress before uploading
- Use responsive images
- Consider lazy loading