Guides to compression and file quality

A working understanding of lossless and lossy compression, quality metrics, and delivery budgets.

Editorial illustration for Lossy vs. lossless compression in plain English

Lossy vs. lossless compression in plain English

Lossless coding removes repetition; lossy coding also removes information judged less important to perception.

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How to choose an image quality setting

A quality slider is not a percentage of retained information and is not standardized across encoders.

10 min read →
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A practical file-size budget for faster websites

Performance improves when each asset has a budget before design and export decisions become fixed.

10 min read →
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PSNR, SSIM, and VMAF: what quality scores miss

Metrics help compare encodes, but no single score understands every texture, viewing condition, or business need.

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How to approach compression & quality

Compression decisions should compare perceptual quality, structural fidelity, decode support, and transfer cost - Not size alone.

Measure the source before moving a quality slider. Lossless compression removes repetition while preserving the original information; lossy compression trades some detail for a smaller output. Compare at least two settings against a real file-size or transfer budget, inspect the most difficult image, audio, or video passage, and keep a high-quality master so later delivery files are not repeatedly re-encoded.

Try each technique with the image compressor, the video file compressor or the MP3 compressor.

Find what consumes the bytes

Measure the source and identify its largest components. Choose lossless optimization or a deliberate lossy target.

Set a quality budget before a size target

Encode two representative settings. Compare artifacts and size in the real delivery context.

Compression comparison protocol

  • The result meets the actual transfer or storage budget.
  • Artifacts are checked in the hardest visual or audible passage.
  • Dimensions, duration, and structure were not reduced accidentally.
  • The uncompressed or highest-quality master remains available.