run

#!/usr/bin/env php
<?php
require 'vendor/autoload.php';

const INPUT_NAME    = __DIR__ . '/assets/input.jpg';
const OUTPUT_NAME_1 = __DIR__ . '/assets/output1.jpg';
const OUTPUT_NAME_2 = __DIR__ . '/assets/output2.jpg';
const OUTPUT_NAME_3 = __DIR__ . '/assets/output3.jpg';

use Intervention\Image\ImageManager;

$manager = new ImageManager([
    'driver' => 'imagick',
]);

if (file_exists(OUTPUT_NAME_1)) {
    unlink(OUTPUT_NAME_1);
}

if (file_exists(OUTPUT_NAME_2)) {
    unlink(OUTPUT_NAME_2);
}

if (file_exists(OUTPUT_NAME_3)) {
    unlink(OUTPUT_NAME_3);
}

$image = $manager->make(INPUT_NAME);
$image->resize(100, null, function ($constraint) {
    $constraint->aspectRatio();
})->save(OUTPUT_NAME_1);

$image = $manager->make(INPUT_NAME);
$image->resize(100, 130, function ($constraint) {
    $constraint->aspectRatio();
})->save(OUTPUT_NAME_2);

$image = $manager->make(INPUT_NAME);
$image->resize(100, 131, function ($constraint) {
    $constraint->aspectRatio();
})->save(OUTPUT_NAME_3);