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Lossy vs Lossless Compression

Understand image compression strategies and pick the best format for your use case.

Quick Summary

  • Lossless: Perfectly preserves original pixels (PNG). Larger files, best for graphics & transparency.
  • Lossy: Slight precision loss for much smaller files (JPEG/WebP/AVIF). Best for photos.
  • Hybrid: WebP/AVIF support both modes; choose per image.

What Is Lossless Compression?

Lossless algorithms reduce size without changing pixel data. PNG uses DEFLATE with smart filters. You can decompress and get the original image back bit-for-bit. Ideal for UI assets, logos, screenshots, and images requiring transparency.

What Is Lossy Compression?

Lossy methods discard imperceptible information to achieve much smaller files. JPEG is ubiquitous for photos. Modern formats like WebP and AVIF provide superior compression efficiency and quality at the same visual fidelity.

When To Use Which Format

  • PNG: Graphics, text overlays, UI, logos, screenshots, transparency.
  • JPEG/WebP/AVIF (lossy): Photographs and complex gradients.
  • WebP/AVIF (lossless): When you need lossless with smaller sizes, where supported.

Practical Workflow

  1. Choose the format based on content (graphics → PNG, photos → WebP/AVIF/JPEG).
  2. Start with moderate quality settings for lossy (e.g., WebP 75–85) and visually inspect.
  3. For PNG, remove metadata and reduce palette where possible.

Related Guides

Deep dive into the format in How PNG Compression Works and learn tactical steps in PNG Optimization Best Practices. For teams, see the Batch Compression Guide.