I'm trying to convert a whole image library to AVIF, what should I watch for?

Converting a whole image library to AVIF can save a lot of space, but there are a few important gotchas to watch for.

1) Compatibility / fallbacks

• AVIF support is good but not universal everywhere.
• Modern browsers support it well, but some older browsers, embedded viewers, email clients, CMS plugins, and desktop software may not.
• If these images are user-facing on the web, keep a fallback format (usually WebP or JPEG/PNG) or use <picture> with multiple sources.

2) Lossy vs lossless

• AVIF can be lossy or lossless.
• For photos, lossy is usually best.
• For graphics, screenshots, UI assets, logos, or images with sharp edges/text, evaluate whether:
  • lossless AVIF works well enough, or
  • you should keep PNG/WebP lossless for some assets.
• Don’t assume AVIF is always smaller or better for every image.

3) Transparency

• AVIF supports alpha transparency.
• But transparent images can sometimes compress differently than expected.
• Test transparent PNGs carefully, especially icons and overlays.

4) Animation support

• AVIF supports animation, but:
  • tooling support may be uneven,
  • encoding can be slower,
  • playback may be less reliable than GIF/WebP in some places.
• If you have animated assets, test them separately.

5) Encoding speed and batch processing

• AVIF encoding is usually much slower than JPEG or WebP.
• For a whole library, expect long batch jobs and consider:
  • parallel processing,
  • queueing,
  • caching results,
  • encoding only the images you actually need.
• Large images may take a lot of CPU time.

6) Quality settings need tuning

• AVIF quality numbers are not directly comparable to JPEG/WebP quality settings.
• A “quality 80” in one encoder may not match another.
• You’ll want to test a few presets on representative images:
  • photos
  • screenshots
  • noisy/low-light images
  • graphics/logos
• Check for:
  • banding
  • color shifts
  • smearing/detail loss
  • edge artifacts

7) Color profiles and metadata

• Make sure your conversion pipeline handles:
  • ICC color profiles
  • EXIF orientation
  • GPS/author metadata if needed
• If you strip metadata to save size, confirm that’s acceptable for your use case.
• Some libraries appear rotated incorrectly if EXIF orientation isn’t normalized before/while converting.

8) HDR / wide-gamut images

• AVIF can support advanced color features, but your pipeline/viewers may not preserve them as expected.
• If you have HDR or wide-gamut assets, test carefully across devices.

9) Image dimensions and resampling

• If you’re converting originals at full resolution, decide whether that’s necessary.
• Often you’ll want:
  • multiple sizes,
  • responsive variants,
  • thumbnails separate from full-size assets.
• AVIF is not a substitute for proper resizing strategy.

10) Decoding performance on clients

• AVIF can be heavier to decode than JPEG/WebP, especially on low-power devices.
• This matters if users will load many images at once or on mobile.
• File size savings may not always translate into better real-world performance if decode cost becomes a bottleneck.

11) Batch conversion pitfalls

Watch for:

• corrupted source files
• very small images where AVIF overhead may outweigh savings
• images already optimized well in JPEG/PNG/WebP
• file naming collisions
• accidental overwriting of originals
• broken scripts that convert everything without checking image type or alpha needs

12) Benchmark before a full migration

Before converting the entire library:

• sample representative images
• compare:
  • file size
  • visual quality
  • encode time
  • decode/load behavior
• keep a rollback path

Practical recommendation

A good approach is:

1. Classify your library: photos, screenshots, logos, transparency, animation.
2. Test AVIF on each class with several quality settings.
3. Keep originals and produce AVIF as an additional derivative.
4. Serve AVIF with fallback if images are user-facing on the web.
5. Automate validation so bad conversions don’t slip through.

If you want, I can help you design a safe conversion workflow or recommend encoder settings for your specific image types.