Imagick

Imagick is the PHP extension that wraps ImageMagick’s MagickWand API. JPEG XL support depends entirely on the ImageMagick library it’s linked against: if ImageMagick was built with libjxl, Imagick reads and writes .jxl like any other format. ImageMagick 7 from current Debian, Ubuntu, Fedora and Homebrew includes libjxl; ImageMagick 6 from older distributions usually doesn’t.

Installation#

# Debian / Ubuntu
sudo apt install php-imagick
# macOS
brew install imagemagick && pecl install imagick

Check that JXL is available:

<?php
var_dump(Imagick::queryFormats('JXL'));  // ["JXL"] when supported, [] otherwise

Basic usage: convert JXL to PNG and back#

<?php
$im = new Imagick('in.jxl');
printf("%d x %d\n", $im->getImageWidth(), $im->getImageHeight());
$im->writeImage('out.png');

$photo = new Imagick('photo.png');
$photo->setImageFormat('jxl');
$photo->setCompressionQuality(90);  // JPEG-like scale; 100 = lossless
$photo->writeImage('photo.jxl');

How to save a lossless JPEG XL#

<?php
$im = new Imagick('screenshot.png');
$im->setCompressionQuality(100);  // ImageMagick maps quality 100 to lossless
$im->writeImage('screenshot.jxl');

How to set effort and distance#

ImageMagick passes jxl: options to libjxl. Set them before reading or writing:

<?php
$im = new Imagick();
$im->setOption('jxl:effort', '9');       // 3-9: slower, smaller
$im->setOption('jxl:distance', '1.0');   // 0 = lossless, 1 = visually lossless
$im->readImage('photo.png');
$im->writeImage('photo.jxl');

How to get JXL dimensions without decoding#

pingImage reads only the header:

<?php
$im = new Imagick();
$im->pingImage('in.jxl');
printf("%d x %d\n", $im->getImageWidth(), $im->getImageHeight());

How to serve a JXL image converted from JPEG#

<?php
$im = new Imagick('photo.jpg');
$im->setImageFormat('jxl');
$im->setCompressionQuality(80);
header('Content-Type: image/jxl');
echo $im->getImageBlob();

The JPEG is decoded and re-encoded; ImageMagick doesn’t do lossless JPEG recompression. Use cjxl for that.

Tips#

• Use setCompressionQuality, not setImageCompressionQuality: ImageMagick’s JXL writer takes the quality from the write settings, not from the image. setOption('jxl:quality', '90') works too.
• Read Exif values with $im->getImageProperties('exif:*').
• Call $im->stripImage() before writing to drop metadata and make the file smaller.