Recursively scans directory for jpg files and saves optimized versions using the same directory structure

optimize.php

<?php
// JPEG quality level
$quality = 85;

// Recursively scan directory and get jpeg images
$sourceDir = __DIR__ . '/original';
$targetDir = __DIR__ . '/optimized';

function getFiles($dir) {
	if(is_dir($dir)) {
		$arr = [];
		$files = glob($dir . '/*.jp*');
		foreach($files as $file) {
			$arr[] = $file;
		}
		$subdirs = glob($dir . '/*', GLOB_ONLYDIR);
		foreach($subdirs as $subdir) {
			$arr = array_merge($arr, getFiles($subdir));
		}
		return $arr;
	}
	else die($dir . ' is not a directory');
}

function optimizeImage($src, $dest, $quality) {
	$info = getimagesize($src);
	if($info['mime'] == 'image/jpeg') {
		$image = imagecreatefromjpeg($src);
		$destDir = substr($dest, 0, strrpos($dest, '/'));
		if(!is_dir($destDir)) mkdir($destDir, 0755, true);
		imagejpeg($image, $dest, $quality);
	}
}

$files = getFiles($sourceDir);

foreach($files as $key => $file) {
	unset($files[$key]);
	$newFile = str_replace($sourceDir, $targetDir, $file);
	optimizeImage($file, $newFile, $quality);
	$fileSize = filesize($file);
	$newFileSize = filesize($newFile);
	$files[$file] = [
		'original' => $fileSize,
		'optimized' => $newFileSize,
		'absolute' =>  $fileSize - $newFileSize,
		'percent' => (100 * ($fileSize - $newFileSize) / $fileSize) . '%'
	];
}

echo json_encode($files);