AVIF Local Support

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AVIF Local Support adds modern AVIF image support to WordPress while keeping compatibility with existing JPEG media. Built by a Boston photographer who just wanted their website to look as good as possible.

GitHub Repository: https://github.com/ddegner/avif-local-support

• Local-first: all processing happens on your own server (works great on local environments like Local, MAMP, Docker) — no external calls.
• Image quality first: uses Imagick when available for high-quality resizing (LANCZOS), corrects EXIF orientation, and preserves ICC color profiles and EXIF/XMP/IPTC metadata when possible.

• Tunable quality and speed: set AVIF quality (0–100) and encoder speed (0–10) to balance fidelity and performance.

• Wraps existing <img> tags in <picture> with an AVIF <source> when an .avif version is present.

• Converts JPEG originals and generated sizes to AVIF on upload, or via a daily/background scan.
• Preserves EXIF/XMP/IPTC metadata and ICC color profiles by default (when using ImageMagick/Imagick).
• WordPress-aware resizing logic enabled by default to avoid double-resizing when generating AVIF sizes from originals.
  • New encoder controls: choose chroma subsampling (4:2:0, 4:2:2, 4:4:4) and bit depth (8/10/12-bit). Defaults: 4:2:0 and 8-bit.
  • Tools include: convert missing AVIFs, upload a test JPEG, and delete all AVIF files in uploads.

How it works

• Front end: Filters common image outputs to add an AVIF <source> ahead of the original JPEG. Browsers that support AVIF will use it; others fall back to JPEG.
• Conversion: Uses Imagick when available (preferred) — with auto-orientation and LANCZOS resizing — or GD with an AVIF encoder. Quality, speed, chroma subsampling, and bit depth are configurable (subsampling/bit depth applied via Imagick when supported).
• Scheduling: Optional daily scan to backfill missing .avif files for existing JPEGs.

Requirements

• PHP 8.0 or later (8.1+ recommended)
• WordPress 6.5 or later
• Imagick PHP extension recommended for best quality and metadata/ICC preservation. GD fallback supported.

Ubuntu/Debian setup (summary)

For local JPEG→AVIF conversion you need either Imagick with AVIF-enabled ImageMagick, or GD with AVIF support:

• Imagick path (recommended)

  • PHP extension: imagick
  • System libraries: ImageMagick built with HEIF/AVIF support (via libheif)
  • Notes: This path enables higher-quality resizing and preserves metadata/ICC profiles

• GD path (fallback)

  • PHP extension: gd built with AVIF support (provides imageavif on PHP 8.1+)
  • Notes: Ensure your distro’s PHP GD is compiled with AVIF; some builds omit it

• Helpful extras

  • PHP exif extension (for orientation handling in the GD fallback)
  • Web server configured to serve .avif as image/avif (Apache/Nginx/LiteSpeed)

Official documentation:
– PHP Imagick installation: https://www.php.net/imagick
– PHP GD installation (AVIF details): https://www.php.net/manual/en/image.installation.php
– ImageMagick format support (AVIF/HEIF): https://imagemagick.org/script/formats.php
– Apache MIME configuration: https://httpd.apache.org/docs/current/mod/mod_mime.html
– Nginx MIME configuration: https://nginx.org/en/docs/http/ngx_http_types_module.html