ALTO Image

Resize, crop and encode images from PHP with lazy execution, predictable output geometry and one decode for multiple derivatives.

         

Image represents one source and one requested output. ImageSet represents several outputs from that source and renders them together. Both are immutable and hold no decoded pixels.

Header inspection, projected dimensions, signatures and derivative paths need no image extension. Rendering uses GD or Imagick.

Features

• Crop by coordinates, anchor, focal point, attention or entropy.
• Preserve ICC profiles or convert pixels to another colour space with Imagick.
• Produce several sizes and formats from one source decode.
• Read files, encoded bytes and streams. Write files or storage backends.
• Encode common raster formats supported by the selected driver. Controls include quality, effort, byte limits, progressive output and lossless output.
• Extract dominant colours and compare images with perceptual hashes.

See crop, colour profile conversion, encoding and analysis.

Installation

Install ALTO Image with Composer:

composer require alto/image

ALTO Image requires PHP 8.3 or later. Rendering requires ext-gd or ext-imagick.

Inspect the available formats and local extension configuration with:

vendor/bin/image doctor

Quick start

use Alto\Image\Image;

Image::open('photo.jpg')
    ->cover(800, 450)
    ->webp(80)
    ->save('hero.webp');

Drivers are detected automatically and safe input limits are applied before decoding.

Command line

Composer installs vendor/bin/image with three subcommands:

Command	Purpose
image doctor	Inspect installed drivers and formats
image info	Read image headers without decoding
image convert	Transform and write one image

Run them through vendor/bin/image. See the command-line reference for arguments, examples and exit codes.

Multiple outputs

Create a responsive image set and write it to a local derivative store:

use Alto\Image\Format;
use Alto\Image\Image;

$results = Image::open('photo.jpg')
    ->cover(ratio: 16 / 9)
    ->widths(640, 960, 1280)
    ->formats(Format::Webp, Format::Avif)
    ->store('public/media');

The resulting ImageSet contains six images in the requested order. Missing outputs are rendered together with one source decode.

Combine outputs with different shapes or qualities using and():

use Alto\Image\Image;

$source = Image::open('upload.jpg');

$results = $source->cover(1600, 900)->webp(82)
    ->and($source->cover(600, 400)->webp(80))
    ->and($source->cover(160, 160)->webp(75))
    ->store('public/media');

Transformations

Named methods cover common geometry and encoding operations:

use Alto\Image\Image;

$image = Image::open('photo.jpg')
    ->fit(1600, 1600)
    ->sharpen()
    ->webp(80);

$size = $image->size();
$key = $image->signature();
$result = $image->render();

Transforms can also be parsed from their stable string representation:

use Alto\Image\Image;
use Alto\Image\Transform;

$transform = Transform::parse('cover=1280x720,g:top-right|sharpen');
$result = Image::open('photo.jpg')
    ->transformedBy($transform)
    ->webp()
    ->render();

Storage

Pass a directory directly for local storage, or use a store object when the application needs paths, pruning or another backend:

use Alto\Image\Image;
use Alto\Image\Store\LocalStore;

$store = new LocalStore('public/media');
$image = Image::open('photo.jpg')->cover(800, 450)->webp();

$path = $store->path($image);
$result = $image->store($store);
$removed = $store->prune(new DateTimeImmutable('-30 days'));

FlysystemStore supports Flysystem adapters. Custom stores implement Store\StoreInterface.

Metadata and safety

Metadata is stripped by default, including EXIF and GPS data. Request only the ICC profile with keepColourProfile(), or all supported metadata with keepMetadata().

use Alto\Image\Image;
use Alto\Image\Limits;

Image::open($upload)
    ->within(new Limits(maxPixels: 20_000_000))
    ->fit(1600, 1600)
    ->webp()
    ->save($destination);

Read SECURITY.md before processing untrusted paths or transform strings. Limit user-supplied transformations to the operations the endpoint needs:

use Alto\Image\Transform;

$transform = Transform::parse(
    $value,
    only: ['cover', 'crop', 'sharpen'],
);

Documentation

• Documentation index
• Getting started
• Transformations
• Image sets
• Encoding
• Analysis
• Storage
• Metadata and safety
• Command line
• Public API
• Drivers

Contributing

Contributions of all kinds are welcome. Visit the project on GitHub to report a bug, suggest a feature, or open a pull request.

Before submitting code, run:

# Runs PHP CS Fixer, PHPStan, and PHPUnit
composer qa

# Runs PHPUnit and enforces 100% line coverage
composer coverage

Changes to public behavior should include tests and documentation. See CONTRIBUTING.md for package-specific guidance.

Support

ALTO Image is open source. You can support its continued development through GitHub Sponsors.

Sharing this package with others or starring it on GitHub is also much appreciated.

License

ALTO Image is released by ALTO PHP under the MIT License.