Image

Getting started

Create an 800 by 450 WebP cover from a supplied image. Follow Installation first and run vendor/bin/image doctor to check that GD or Imagick can read PNG and write WebP.

Download the example source into your project as source.png. This original ALTO documentation illustration is 1200 by 800 pixels and is distributed under the repository's MIT license.

Save this as thumbnail.php beside vendor/:

<?php

require __DIR__.'/vendor/autoload.php';

use Alto\Image\Image;

$output = __DIR__.'/public';
if (!is_dir($output)) {
    mkdir($output, 0775, true);
}

$result = Image::open(__DIR__.'/source.png')
    ->cover(800, 450)
    ->webp(80)
    ->save($output.'/hero.webp');

printf("%d x %d %s\n", $result->size()->width, $result->size()->height, $result->format()->value);

Run php thumbnail.php. It writes public/hero.webp and prints:

800 x 450 webp
Source: 1200 x 800 Cover: 800 x 450
Original landscape illustration with sky, hills, and a sun Actual WebP cover, cropped vertically to a 16:9 frame

cover() fills the requested box and crops the excess. The source remains unchanged. The default avoids enlargement, so use a sufficiently large source when reproducing these exact dimensions. See Cover for scaling and crop placement.

Understand the result

The request is immutable and lazy: pixel decoding happens at save() here. The .webp filename does not select the format; the explicit webp(80) call does. ALTO applies the source's display orientation when rendering.

The returned Result contains encoded bytes, actual dimensions and format, driver, duration, and any degradations. A degradation means the chosen driver approximated part of the request; see driver capabilities. Encoded sizes and pixels can vary between driver versions.

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