Passing detected faces to imgix

faces.php

<?php
// not tested
// would go into your theme's functions.php
add_filter('ilab-imgix-filter-parameters',function($params, $size, $id, $meta){
	if (isset($meta['faces']) && is_array($meta['faces'])) {
		$firstFace = $meta['faces'][0];

		$rect = $firstFace['BoundingBox'];
		list($width, $height, $left, $top) = array_values($rect);
		
		$params['not_sure_what_it_is'] = "$left,$top,$width,$height";
	}
	return $params;
}, 10, 4);